Electronics

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Exploring Electronics on a Budget

This page shares components and materials for exploring electronics and building interesting things on a budget. These are explored in our face-to-face and online engineering, computing, and applied technology masterclasses & workshops.

2026 : We’ve split the page as it was getting long and a slow load. If you come across a link that redirects you to this page, just click the next part and search there.

We cover:

Electronic Circuit Fundamentals including resistors, capacitors, transistors (more useful than relays), diodes, physical user interface elements: switches, knobs, sliders and other controls, and basic interactive elements: LEDs, buzzer, speakers
Advanced Electronics including digital logic, integrated circuits (ICs), low cost microcontrollers, large scale integration (LSI) components such as application specific ICs (ASICs), and very large scale integration (VLSI) components including CPLDs and FPGAs
Sensors & Microcontrollers & Embedded Systems includes sensors, communications (serial, SPI, I2C, RF/RC, NFC, WiFi, Bluetooth, Zigbee), displays (OLED, TFT), motors/actuators, which are essential to building autonomous systems, smart systems, and robotics.

For more information about our masterclasses in technology, and schedule of events across North London, Hertfordshire, and Buckinghamshire, see our website.

Some examples:

Gallery 1 – kid-friendly projects,
Gallery 2 – 13-key piano based on tunable analog oscillators,
Gallery 3 – microcontrollers and sensors,
Gallery 4 – motors, actuators, and 3-D motion control (in prep)
Gallery 5 – complex sound effects generator, beats sequencer/drum machine, fully programmable digital piano on PCB (in prep)
Gallery 6 – talking sensors and voice-controlled hardware
Product Concepts (in prep)

What to Buy, When to Buy It

An initial investment of under £105 (Kits 1,2,3) is enough to get started with electronics, sensors, and microcontrollers, including essential equipment and software.
From here, capabilities can be added through expansion packs ranging from £5 to £20. These add increasingly more advanced capabilities.
To invest in tools & infrastructure, we provide Tool Packs that lead to an increasingly well-stocked electronics workshop including capabilities for prototyping (soldering, heat-shrink, hot-glue), signal analysis (signal generator, oscillosope), panel/enclosure construction (drill, saw).
If you go through all the capabilities here, you can get a comprehensive capability for approx. £200. As a hobby, this is similar to what one might spend if one were serious about a sport such as tennis (multiple rackets, balls, shoes, case, club membership, and various accessories).
So start frugally, then gradually invest more as interest, workshop space, and available time/budget allow. Along the way you’ll be building some neat stuff.
We provide all equipment in our courses. Just bring yourself/your child, with enthusiasm and the willingness to get stuck in!

Quick overview:

Power: 9V batteries are probably the easiest to work with – you can get low-density zinc carbon batteries which are much more forgiving if you short them (the high internal resistance means they can’t discharge catastrophically in the way alkaline or lithium batteries can).
You’ll need a snap connector, and the easiest way is to solder solid core 22 AWG ends to the flying leads. That gets you plugged into any breadboard. This will work with any circuit that is tolerant of 9V. For chips, you’ll need a step-down converter. You can use the cheap and cheerful LM7805, or, for a bit more $ and a lot more efficiency, the adjustable voltage LM2596 will provide even heavy draws up to 2A per channel for motors etc (though you’ll need alkaline or lithium batteries to be able to draw anything the 150-300mA that the motors will require, even at 5V). It has screw terminals so your flying leads can screw right in, no soldering needed. (Some people like the MB-102 – I find it too complicated for most breadboards (who needs 5 different ways to power a circuit. If you’re using a battery, you’ll now need to solder on a plug-in jack connector, or for wall power, you’ll need a 9V 2A wallwart AC-DC converter with jack connector, or through a USB power supply (5V) using a standard USB A male end USB A male to A male power cable.)
On the portable end, I recommend a 3V CR2032 lithium coin cell battery in a breadboarda-ble holder with and a 5V tiny boost converter. This works great for low power applications (less than 10-15mA). For heavier draws, a 1.5V AAA cell should give the extra oomph, and the 5V tiny boost converter will jack up the voltage and keep it stable. (If you don’t want the standalone tiny boost converter, you can use the
Lilypad 5V DC boost converter instead – here
Sensors: £4.99 each sensor
Microcontroller: Arduino Nano (Atmega328P) breadboardable microcontroller platform with USB-mini programming cable, £27 for 4pc
Mini Pliers for bending component leads for insertion into breadboards/placing components
Multimeter with Test hook mini-grabber multi-meter probe (banana plug) for electrical measurements and testing, and 9V battery
Software: Use our MasterWorking Forth for a rapid ramp-up into hardware and software programming. Request via comment form. Otherwise you can try Arduino IDE (C-based Arduino compiler), or MicroPython.

Expansion Packs

Head-aimable USB rechargeable light and 30x Lighted Magnifying lens for proper illumination/magnification.
Test hook mini-grabber cables 2 pairs double-ended (2 pairs recommended per child for working with 3-8 year olds)
USB extension cable: M-F extension 1m , USB-mini, USB-micro, USB standard 2.0 1m
Universal DC USB buck-boost converter power supply with display
Batteries Targeted power supplies, batteries, holders, button/coin cells, AAA, Lithium 3V CR123, Micro 5V DC-DC CE012 boost converter. Custom wallwarts (eg 5V 2A) etc.
Smaller microcontrollers ATtiny85, ATtiny84, STM8/Trinket.
ATtiny Sparkfun Tiny AVR USB Programmer (£17) or Make Your Own for less than £5!

Replenishment of items can be made individually as needed from the list below:

Solderless Breadboards (x2 medium 400 tie-points, x5 small 170-tie points), Jumper Wires (medium 20cm and short 10cm), Solid Gauge Hookup Wire
LEDs small 3mm red, yellow, blue, green white
Resistors 1/4W mixed values and Trimmer pots
Capacitors – mixed values
Switches – for 4 basic types (1P2T slide switch, momentary tactile button normally open, latching tactile button, contact switch)
Transistors, mainly 2N2222 and a few TIP122
Buzzers and Speakers (8-ohm, 0.5W, 1W, 3W, 5W)
Diodes
Parts Storage Boxes

Advanced components and ICs can be selected based on particular projects:

Potentiometers including Audio (A-taper) pots, Linear (B-taper) pots, knobs for 6mm shafts
Analog ICs: Timer Chip (555) Audio Amplifier (386)
OLED Display
Super Micro DC-DC 5V Boost Converter CE012
DIP switches (5, 8, 10 switches, DIP-10, DIP-16, DIP-20)
Logic ICs Buy low power ICs — power budget grows quickly when using multiple complex ICs, and anything with total power >100mA will be consuming batteries quickly — a 3V, 1500mAh CR123 battery will last 900mA at 5V (ignoring conversion loss), which is 6hrs (at 140mA digi piano) and 5hrs (at 170mA digi piano+76477 synth) Normal ICs draw more than LS (Schottkey) which in turn draw up to 1000x more current than HC or HCT (CMOS) chips. TTL vs. CMOS chips explained. Integrated Circuits (ICs) – Sparkfun introduction. ICs come in chip families, with different attributes: TTL family are the original 74xxx chips. Then there are 74Sxxx and 74Fxxx. Then 74LSxxx TTL family (inputs float to high). Also CD4000 family were introduced by RCA in 1968 using CMOS technology as lower power alternatives to the 74xxx series. HC/HCT family are CMOS logic 74HCxxx or 74HCTxxx, inputs can float to anything. (Note – good design should leave no inputs floating no matter what logic family is being used.) (Note, HC and LS don’t mix well, so consider HCT). Then there’s AHC/AHCT which can also work with breadboards, and are half the power of HC/HCT and 3x faster. And then we get to chips faster than a nanosecond which are too fast for breadboards, e.g. AC or LVI For production designs best to source 74HC/74HCT chips. Further reading on logic families.
RF-Nano (Nano+NRF24L01) for 2.4 GHz remote control via wireless radio frequency (RF)

Kit 2A – PCB Prototype Building Equipment

Soldering Kit (including iron, safety stand, case, tweezers)
Additional Soldering Accessories – (flux pen 80p, swarf cleaner £1.30, tip tinner £6, copper alligator clips for heat dissipation £5, PCB-jib £8, thin gauge lead-free solder £9, rubber desoldering pump £3, curved soldering tips pencil point £7, soldering mat £11)
Wire strippers, £9
Wire cutters – £2
Safety glasses – £2.50
Wicker storage basket (heat resistant)

Kit 2B – PCB Prototyping Supplies – £40

Prototype PCBs for point-to-point wiring – £12
Wire Wrap wire (30 AWG) or Hookup Wire (22 AWG for breadboarding) – £4
Standoffs M3 and M2 – £5
Headers, PCB Jumpers – £10
Screw Terminal connectors, DC Barrel connectors and Plugs – £9

Kit 3 – Motor Components – £80

Power Resistors, 1/2W, 1W, 2W, 3W, and 6W low ohm resistors (5R to 100R), — £8 useful for audio and motor applications
Stepper Motors — £6
Darlington arrays (high current step motor driver IC) — £3.50
Gears and Pulleys — £4
Low-slip pulley bands and pulleys various sizes for amplifying transmission/drive ratio — £12
DC motors with reducing gearboxes – £15
Cams and Rack & Pinion, Steering assembly
Servo motors – £20
Wheels and Axles – £15
Candy Floss wooden sticks for chassis frame – £9 for 100pc
1.5mm and 2.5mm drill bits for drilling holders for 2mm axles – £5
Shaft couplers for mating 5mm step motor shaft with 2mm axle shaft – £5

Kit 4 – Signal Analysis – £32

Oscilloscope – £19
Signal/Function Generator – £9
BNC cables – £4

Kit 5 Equipment to build Prototype Assemblies, incl. Panel Mount, Enclosure, Wiring Harness – £81

Cordless drill, drill bits, step drill bit, Forstner bit, plug cutter bit – £50
Hot Glue gun – £17
Saws for cutting – £10
Heat shrink gun + Heat shrink warp – £11
Small screw driver set – £5

Computer Aided Design (CAD) and Manufacturing (CAM)

EasyCAD
TinyCad (schematic capture) (awesome: 20MB, quick, easy, no fuss, plenty of design library elements, creates PCB netlist, free). Orders of magnitude smaller than KiCAD, Eagle, or AutoCAD.
Kludge + MsPaint: quicker web-based one-off schematic creator. User interface is click-and-click instead of click-and-drag: clicking a tile moves it to “Current tile”, then you click in the grid (not drag), and whatever is in current tile snaps to the appropriate spot on the grid. Many more parts are available from its predecessor Klunky. Integrated tile editor would be best new feature to allow new parts. Second best new feature would be text tool to add part values and other annotations… I’m doing both in an export step (screenshot to mspaint). Could also export SVG to Inkscape. Using Kludge’s lamp symbol as generic placeholder, then dropping on top the desired symbol (eg. speaker) from stock schematic symbol images. Here’s an example (left image):

Example circuit created with Kludge and annotated in MsPaint.
FreePCB (PCB design) (download Portable Zip from MathSciTech.org)
VeeCAD (prototype layout). To export Netlist from TinyCAD that can be used in VeeCAD must use VeeCAD libraries in TinyCad, or make sure that the Package names used in TinyCad exists in VeeCAD.
TinyCAD webpage collects user submitted parts/footprints.
Schematic capture software, TinyCAD or KiCAD, then TinyCAD + FreePCB for complete schematic capture and PCB layout and TinyCAD + VeeCAD for schematic capture to breadboard layout. Discussion Netlist converter (opencad)
KiCAD: is designed around the following workflow: Make schematic & add values to symbols, annotate schematic symbols, Assign Footprints, import to layout editor. In EAGLE, every part has a footprint assigned or some variants. Once you add a resistor, you already chose its associated footprint. In KiCAD, the philosophy is different: You can pick a resistor from the symbol library and add as many as you like. After placing none of them will have a footprint assigned. You now can assign footprints to each resistor (This can of course also be done in a central place for bulk assignment). KiCAD also does not annotate for you. It keeps parts unannotated (eg L?, C?) until you annotate them. It makes sense, though: After placing, automatic assignment of names is not neccessary. It only becomes important when assigning footprints to symbols before the PCB routing. This can and should be done in bulk anyway. In KiCAD, symbols and footprints are intended to be separate in different libraries. This allows for re-use of standard footprints like SO8 or QFP32. (Jan Kruger, Hackaday)
Schematic and PCB layout software FreePCB or KiCAD
PCB Basics (Sparkfun enlightenment)
Printing PCBs in your home — for $4,000
eForth for STM8S gadgets
Forth cross-compiler for 8051, AVR, ARM Cortex-M, MSP430, PIC, and STM8 microcontrollers
TeachMePCB.com
PCB Checklist
Linkage Mechanism Designer/Simulator
One-Off Prototyping as a Service, from laser cutting to 3D printing
PCB Design & Board Assembly, Futurlec

The Equipment List

Items are grouped below by function and chosen based on capability and (low) cost. I have included links (UK based) where each item can be bought inexpensively, with the choice to accept longer delivery times for lower price. (Note: Since the COVID-19 pandemic, electronics component prices have risen 50% to 100% on many items. I show this by listing the lowest price at which an item had previously been sold, and current pricing. If the different is large, it is worth doing another search on both Ebay and Amazon, as there may be new sellers offering sharper pricing.)

0. Guidebooks

A. Equipment (long term investment)

B. Components & Supplies

C. Power Supplies (Batteries, Holders, Converters) Fuses, & Heat Sinks

D. Integrated Chips – Analog, Audio, and Digital Logic chips (incl. 555, LM386, 74xxx chips, ALU)

E. Microcontrollers and FPGAs

F. Sensors & Communications

G. Motors, Machines, and Robotics

H. Storage (Cases, Containers)

0. Recommended References

Make: Electronics, by Charles Platt, Maker Media, 1st ed. 2009, 2nd ed. 2015, 3rd ed. £20 Oct 31, 2021. This is an excellent hands-on, learning-by-discovery primer for the new electronics enthusiast: burn things out, mess things up; that’s how you learn. Audience: mature teen or interested adult, intended for self-study.
Make: More Electronics, by Charles Platt, Maker Media, 2014, £17.50 Journey Deep into the World of Logic Chips, Amplifiers, Sensors, and Randomicity
Easy Electronics, by Charles Platt, very easy starter book for children under 10yo, £7.53 next day, 50 pages.
Art of Electronics, by Paul Horowitz, £57 next day, or Third Edition free on Archive (digital PDF)
Mobile Robotics: Inspiration to Implementation, Joseph Jones & Anita Flynn, 1st ed 1997, £6, 2nd ed 1999, £3.50 — Get the 2nd Edition, it is much expanded!
Interfacing Microcomputers to the Real World, by Murray Sargent & Richard Shoemaker, 1981, £7 used, or $10 in US
Starting Forth, by Leo Brodie, £12.09, very easy self-starter programming book in Forth for smart children under 12yo. Forth (GForth) can be used to interface with microcontrollers using existing Forths, or my 3-instructions Forth for Arduino.
Principles of Computer Hardware by Alan Clements, 3rd Ed., 2000, Oxford University Press, £3.50 used An excellent introduction to Digital Logic and Computer Architecture. Uses Digital Works v2.0 (freeware, download here) to teach digital logic design. Fourth edition 2006 (£50 new/£17 used) appears to have essentially the same content as the 3rd edition, so you may wish to save the extra cost.
SparkFun Electronics Tutorials – comprehensive tutorials on many topics relevant to electronics makers
Comms Protocols:
UART (Asynchronous Serial)
I2C
SPI (4-wire, synchronous serial): my wiring convention: CLOCK=orange, LATCH=yellow, DATA=green (for shift registers). Arduino with Atmega328P MCU, ATtiny85 (SPI in software), ATtiny has USI in hardware which can be tweaked to use SPI protocol | SPI terminology – Controller / Peripheral. COPI/CIPO. Chip Select CS. Note: Historical wrongs need to be righted. See here for the Sparkfun initiative to rename SPI pins COPI/CIPO, CS Controller/Peripheral, Chip Select | Official Declaration — no more master/slave terminology in computing
| SPI comms – Excellent SPI bare metal tutorial (Steve Mansfield-Devine)
| I2C comms – Excellent I2C bare metal tutorial (Steve Mansfield-Devine)

New SPI pin names, righting historical wrongs: COPI/CIPO/CS
Controller Out / Peripheral In, Chip Select
STEM Summer Workshops
Article: How to Think about Engineered Solutions? (Sep 17, 2019)
Article: Electronics: Experiments & Exercises (Sep 15, 2019)

A. Equipment

How to use a Multimeter (Sparkfun)

Digital Multimeter – Budget (ESSENTIAL) You can get a lot of value in the sub-£15 category. Buy 2 units so can simultaneously measure current and voltage in a circuit. For advanced work you will need 3 units (unregulated voltage, regulated voltage, and current), still cheaper (<£30) vs. c.£100 for a multi-channel wireless multimeter Pokit-Pro £100 | How To Guide (Sparkfun)
What to look for: a) VDC down to 2V, b) R (resistance), c) ADC down to at least 20mA, d) VAC down to at least 20mA, e) F (capacitance), f) Audible Continuity check, g) diode test, h) manual ranging ¹ with dials coloured so DC are all one color, and AC are another, i) power button (to make auto-shutoff not irritating), j) hFE for transistor DC gain
- RECOMMENDED: DT-9205A £15.90 (Amazon) or DT-9205B
  Note, some of these are 2xAAA batteries, and some are 1x9V battery. Look after receiving. Also, some of these have an annoying beep after each rotary knob turn.
- NOT VERSATILE ENOUGH. Compact (but no capacitance measurement and AC voltage not for electronic ranges i.e. no 2mV or 20mV ranges, and voltage measurement is 4-5mV off): £8.00
- UNRELIABLE: Baoblaze AN819A (1star), £12. Two units each lasted less than a year, then started giving erratic measurements. Auto-power-off (APO) feature is annoying as it is based off a timer whether unit is in use or not. Once auto-power goes off (APO), it requires twisting the dial back to Off to restart, inconvenient when in the midst of measurements.
- GOOD. Out of stock since 2017: Ultrics UT0021D, £10, 5 stars, lasted 3 yrs.
- Advanced: Also does Temperature and Frequency, £42
- Advanced: PokitPro multi-channel multimeter
- Advanced: Combination o’scope & multimeter: Owon HD272 £140, HD242 £110 | Hantek 2D72 £151
Notes:
- [1] Multimeter probes require banana plugs on one end. Recommended probes are test hook clip (aka minigrabber or retractable hook clip), as these can grip thin resistor wires easily, and hold themselves in place, freeing up both your hands. (Less recommended options are pointed probe and alligator clip.)
- [2] Not critical to have frequency or temperature functions (see oscilloscope below).
- [3] How low-cost mass market multi-meters are made using How mass-market multi-meters are manufactured using chip-on-board COB technology to pot the electronics in an epoxy. The PCBs then have a glob/blob with the bare IC wafer underneath (picture).)
- [5] Yellow multimeters are apparently violating a Fluke trademark (2014, Sparkfun), which was resolved between Sparkfun and Fluke.
Test Hook Cable (aka mini grabber probe) (ESSENTIAL)
Test hook cables are excellent for securely gripping bare wire or individual IC pins to allow precise measurement in tight spots without shorting adjacent pins. They are able to be operated by general as young as 3.5 years unlike alligator clips which are too stiff for little fingers (until c.7 yrs). Grabber probe cables provide great hands-on circuit practice and visual demonstration of connections between components, for younger kids in a learning session.
1. for Multimeter (banana plug to minigrabber): Lowest price: £2.04/pair. Currently: £3.30 right-angle or £2.63 right-angle or £2.70 straight If your multimeter display starts to wobble/vary, check your cables. Cheap cables (not listed) can be problematic. If cables are fine, it may be your multimeter.
2. double-ended: £9 for 5pc, 50cm (£1.80ea).
3. grabber-breadboard: male or female end. £6.23 for 10pc (62p ea) or 56p ea (MOQ30), or £6.50 for 10pc (65p ea) or negotiate (seller1, seller2), £11.50 for 10pc (£1.15ea), next day, or £11 for 10 (£1.10 ea) or £16 for 10 (£1.60 ea)
4. probe only (no cable): Grabber Probes, 20pcs for £1.66 (8p ea.)
  Robust grabber probes with smooth action. Each grabber probe has a cap which can be removed to allow soldering any wire to the end to make custom test probles.
Alligator clips are harder for young children to open due to the finger strength required (appropriate for age 7+), their teeth are less effective in gripping unsheathed wire, and they cannot probe IC or PCB pins easily without shorting adjacent pins. for Multimeter: Alligator Clip to Banana Plug 70p/pair, double-ended: alligator clips (10 for £1.68 (17p ea.)
Wire Strippers & Pliers (ESSENTIAL)
1. Wire Strippers, ensure 20-30 wire gauge (AWG), Lowest price: £6.57, currently: £9 next day. Essential for building circuits using hookup or flexi-wire instead of pre-made jumper wires. Use with a twisting action for smooth cutting and stripping. Has a crimper slot as well for crimping wire into pin headers.
2. Mini-Pliers: Get the red & black ones, as these are safest for little hands. £7 Hilka red/black. Easily bend hookup wire into jumper wires, insert components into solderless breadboard, and as a crimp tool for crimping wire into header pins. As a 2nd pair, consider Needle-Nosed (Extra-Long-Nosed) Pliers: £2.50 or £1.18 (Add-on item) which are useful if you need to hold two ends in order to manipulate one end with force – e.g. when sliding insulation down a jumper wire.
3. Wire / Side / Flush Cutters: Lowest price: £1.63 for lower end (B3180) cutters that ended up getting blunt. Higher end: Amtech 8″ Pro Side Cutting Plier B0640 £4.25 or Amtech 6″ Pro Side Cutting Plier B0635 or Amtech B3180 (Mini Side Cutting Plier) – not recommended – (required when creating PCBs to snip ends left behind after soldering. Note! Wear safety eye-glasses when doing this, as the ends are often hard and fly off with force and at random directions). If it gets blunt after a time, discard and get a new one. (mine lasted 3 years of frequent snipping of soldered wire from PCBs)
4. Flush cutters – 4pc for £4 (£1 ea) next day or 2pc for £4 (£2 ea) next day | professional angled jaws £6.30
Head-aimable Worklight, Magnification & Safety Glasses (ESSENTIAL) £13 for 1 of each
Don’t cut corners on good aimable lighting. Electronics requires focusing your eyes on tiny parts and thin leads, and requires precision insertions. You will save your/your children’s eyes by having bright, aimable lighting. The portability of a headlamp means you can work anywhere with the same quality illumination. Recommend to buy two, so you always have one ready to use while the other is charging. Frustration = light giving out at a critical moment.
1. Work headlight/headlamp, USB rechargeable: 2pc for £14 (£7 ea) same day or gesture activated styles. Great for illumination while doing small precision work. Removes requirement for a bright desk-lamp. Recommend to buy two, so you always have one ready to use while the other is charging.
2. Magnifying Lens: Handheld – Needing something stronger. Trying this one: £6 for 30x, 60x, 90x in a compact, portable, lightweight form factor. Also have this one: Lighted 30x, £9 next day or £12 next day, 15x, £10.50 same day (integrated light helpful for reading ICs). Alternatives: (1) Trifold lowest price 15x £3, currently: 10x for £5.50, or (2) unlighted 6.5x for £6. or (3) Handsfree: LED rechargeable headset, 1-3.5x, £23 same day
  20x+ resolution is necessary to read the small print codes on some capacitors without which you cannot identify them without measuring the capacitance of each (slow!). 3x-5x Pocket magnifiers don’t have enough resolution. Illuminated lens is necessary to be able to make out etchings on electronics chips, tilting till the light catches it just right.
3. Safety Glasses: Children (2-16 yrs), £2 ea, Adult: lowest price £1.30, currently £2.93 next day. Better safe than sorry. A child’s eye would be a terrible thing to lose. Your own eye would also be a shame to lose.
Soldering: The Fine Art of Fine Soldering

Soldering well takes practice and requires some essential equipment. The following is some advice learned from dozens of hours becoming proficient.
1. Get a decent soldering iron and safety stand: Tabiger 60W adjustable temperature (200-400*C) soldering iron with on/off switch and LED indicator. Get a nice carry case and safety stand (ring type enclosed), and a few extra tips. Assemble the rest of what you need yourself. Iron only. The iron is well balanced, reliable, and long-lasting (I’ve used mine for 4 years with no issues). Minor downside is the screw that holds the tips in place which is fiddly and seems to lose thread integrity, but overall this is a nice iron and recommended.
2. Set tip temperature higher than you think, e.g. 300-350*C. This allows soldering more quickly (2 sec total: 1 sec heat pin, 1 sec apply solder and remove), and heating the metal for less time, which minimizes unnecessary heat transfer into component (avoids e.g. switches fail from excesive heat).
3. Assemble your soldering kit to contain 15 ADDITIONAL COMPONENTS (besides iron, carry case, and safety stand above) — see links below
  1. lead-free thin gauge solder (0.6mm),
  2. curved pencil tip (0.5mm) soldering tips,
  3. tip tinner for protecting your tips after use,
  4. swarf cleaner (avoid water and sponge which introduces micro-cracks into the tips),
  5. soldering mat (to avoid burns to the table from dropping molten solder)
  6. 30 AWG super thin wire-wrap wire for point-to-point soldering,
  7. head wearable light for proper illumination (your eyes will suffer if you don’t have enough light!),
  8. flux pen (for smoother flow of solder from iron tip to components),
  9. copper alligator clips (for faster heat dissipation after soldering complete),
  10. rubber desoldering pump (for correcting mistakes, much easier than a solder wick, and more suction than the conventional solder sucker triggers),
  11. 170-tie point breadboard (to avoid need for helping hand),
  12. digital multimeter for testing connectivity.
  13. a PCB-jig once you start soldering PCBs,
  14. FR4 double-sided PCBs,
  15. M2 standoffs and nuts
4. Plan your DIY PCB board: 1) Prototype working model on breadboards, 2) Plan PCB design layout, 3) Place components (I use a drop of hot glue to keep them in position), 4) Solder components in place, 5) Bend intrinsic component wires and solder joints (use flux), 7) Measure, cut, strip, and add topside main bus/trunk wires using 22AWG hookup wire – keep stripped ends long to bend to connect to points/joints, 8) Measure, cut, strip, and add point-to-point wiring using 30 AWG wire-wrap soldering wire, 9) Remember to TEST AS YOU GO! (from step 5 on).
5. Invest in 30 AWG super thin wire wrap wire for point-to-point soldering – with conventional breadboard 22 AWG solid core wire, you bend the wires in your components to bridge between pins and make connections. (Don’t build solder bridges between adjacent pins.) For pin-to-pin connections I’ve come to love using thin gauge (30 AWG solid core) soldering wire instead of 22 AWG solid core breadboard wire. It’s quicker, easier, allows wiring in narrow spaces, making dense connections, and does not take up holes on the PCB. Everything goes on the back of the PCB keeping the visible top neat. In this way it’s akin to PCB routed wires, except that wiring errors are easy to connect – just tap the wire for 1/4 second with soldering iron and simultaneously pull the soldering wire away with tweezers copper alligator clips | Use wire-wrapping wire to do point-to-point soldering by attaching directly to soldered pins of components on back of proto PCB board.
6. Allow for time! Your assembly time will decrease dramatically as you get more proficient (practice!) Once proficient, rule of thumb might be c. 2 mins per soldered connection. So a 13-key keyboard takes (130 connctions) takes c.4 hrs. A 4 IC board with 32 LEDs (the shift register/programmable digital piano for example), with c.200 soldered connections on an Electrocookie PCB (one with some connected trace pattern), takes c.7 hrs. When starting out, it might take 6 min per connection to figure everything out, so a 20 connection project may take 2 hours of assembly time. By your 4th board you should be close to reasonably proficient.
7. Test as you go – If there is a connectivity problem, you can fix it immediately instead of troubleshooting later to find where the fault is (painful) | see digital multimeters. Fixing mistakes can take 3-10x longer than getting it right, so go slowly, methodically, don’t rush!
8. From DIY PCB proof of concept to turn-key assembly Once you’re happy with a DIY PCB, it may be more cost effective to lay out your own PCB and get it turn-key assembled (see eg JLC PCB in the References below).
RECOMMENDED ADDITIONAL SOLDERING COMPONENTS FOR SERIOUS DIY
1. Buy lead-free solder for for health reasons, even if it is harder to work with and more expensive. Buy 0.6mm for easier soldering of delicate parts. | Types of Solder, Lead Poisoning | Electronic Solder (rosin core): 0.6mm 100g for £8.50 Lead Free (Sn99/Ag0.3/Cu0.7/Flux 2.0%) rosin core.
2. Thin Curved Pencil End Tips: 10pc for £7 (70p ea) same day or 5pc for £7.60 (£1.52 ea) same day Standard tips: 10pcs T-I £6 (60p ea) or 15pcs mixed type £7 (46p ea). Replacement Tips: for normal soldering work 900M-T-B, for fine pin header soldering work 900M-T-I.
3. Use tip tinner to protect your tips from oxidation. Coat the tip after use before letting the iron cool. | Tip Tinner: £5.50 – reconditions iron tips to pristine condition by recoating the tip, prevents oxidation damage and provides even heat distribution. Must have.
4. Clean the tip with swarf not sponge and water. Between uses, or when the tip has accumulated solder, clean the tip by rubbing it (up and down motion) in swarf. Don’t use sponge and water as it can cause cracks in the tip due to the abrupt induced temperature change. | Swarf soldering iron tip cleaner, £2.87 pad and tin, £1.31 pad only Works brilliantly with tip tinner. Keeps soldering tip shiny and sharp. Much better than sponge and water. Have hot glued this and the can of tip tinner to the sponge location of my soldering stand for easy one-handed access.
5. Wire wrap wire 30 AWG, 8 colors, 15m each: £4 next day or £2.40 4 weeks. (Only downside is they are all wrapped together. Would prefer each color spooled separately) | Don’t use magnet wire which has insulation which cannot be stripped but must be burned with a soldering iron to remove, but insulation is gives off toxic fumes. | Magnet wire (0.2mm, #32 gauge), Red, £2 for 100m | How to Solder Tiny Things, example of wiring using copper winding wire, or here. Step-by-step here. | Extreme Soldering (highly recommended to learn advanced techniques) | Examples of Point-to-point soldering on Protoboard PCB using Wire Wrap wires | To use wire wrap wire you will need a pair of tweezers. I recommend copper alligator clips.
6. Learn how to solder without requiring complicated helping hands, which are expensive, take up space, and in my view are more awkward than they are worth. A simple copper alligator clip, a 170-tie point breadboard, and a PCB-jig for swiveling the pcb easily, are all you really need. | PCB holder Jig / vice £8. Useful for soldering PCBs and as a general third-hand. Can add a small breadboard to aid holding smaller parts, e.g. wires. Video tip for keeping components in the PCB while soldering. | Technique for using only your own hands: use copper alligator clip to hold tip-stripped soldering/breadboard wire raised (on a soldering mat to protect table surface from burns if molten solder falls), and apply solder to the exposed tip, apply solder flux from flux pen to improve the speed with which solder flows to where you want it, reducing sticking to the soldering iron tip. Do the same to the mating pin/wire (apply flux and then solder). Keeping one wire/component anchored, you can now bring the other in close and apply iron to heat both. The solder already coating both wires/pins should fuse creating a solid connection.
7. Solid Copper Alligator Clip Heat Sinks: lowest: Large 43.5mm, £1.23 ea. (MOQ4) or 50mm, £2.25 ea (MOQ4). Small Ones (<40mm) are not useful. These clips act as heat sinks when soldering sensitive electrical components (LEDs, ICs, etc.), as copper is a better heat conductor than steel. I attach these to the Helping Hand tool and then clip the components into these copper jaws. They are also very useful when running microcontrollers to drive motors or sensors until the current draws/settings are figured out, to prevent DC regulators and MCUs from overheating. Also for attaching copper plates/heat sinks to stepper motor casings, which heat quickly under constant load.
8. Rosin flux pen #951, Currently £5 (lowest price was 80p, Yosker; then £2.14!) Has solder in it (this paste does not). Helps speed up soldering, allows smooth and even application of solder to the wires, and helps it to flow into place before hardening. Use with a breadboard means can apply solder to each wire separately then briefly apply heat to hold them together melting their joint solder coats. In this way no third-hand equipment is needed, but the flux pen is necessary to get the solder to adhere to the individual wires.
9. Soldering Mat protects table/floor from burns due to molten solder drips. The mat has a non-stick coating which solder does not stick to (neither does hot glue!) | Soldering/Hot glue Mat £11. Or with built-in solder holder, £16
10. a solder sucker can be a lifesaver if you need to remove excess solder or separate pins that have accidentally been flowed together. | Removing Solder from PCB Holes | Rubber suction bulb, £2.50 or £3.00 for heavy duty desoldering. This versatile rubber suction pump has plenty of suction and works much better than dedicated desoldering pumps. The high suction pulls heated solder out of pcb joints instantly. Note, due to the narrow neck, cooled solder inside the bulb is too big to eject, so at some point this will fill completely with solder, and need to be replaced. But the price point works for this, and incentivizes fewer soldering errors.
11. use FR4 double-sided pcb boards instead of phenol single-sided boards (the rings around the PCB holes lift off with excess heat, and the board burns easily, rendering holes useless). | Get some M2 standoffs and nuts to stand the finished PCB above the table to protect the reverse side from pressure as the top side is interacted with.
  References:
  - Extreme Soldering (SMT chips onto a normal PCB)
  - Soldering Tutorial (Sparkfun)
  - Soldering tips, from equipment to method
  - Surface Mount Soldering with a standard soldering iron, key is to look for the larger SMT/SMD part dimensions: 0805, 1008, and 1206, etc., see Hackaday article
  - Common soldering mistakes (useful pictures)
  - Extreme Soldering (highly recommended to learn advanced techniques)
  - Examples of Point-to-point soldering on Protoboard PCB using Wire Wrap wire 30 AWG
  - PCB layout principles (for veroboard, but the general guidelines are true also for point-to-point PCBs).
  - See Soldering Tips (search solder)
  - Turnkey PCB production: Specifying the design for a PCB Contract Manufacturer, Gerber file format (Wikipedia), single vs. multi-layer PCB.
  - PCB Design for Contract Manufacturing and PCB Assembly: PCB Train £150 setup cost, £30 incremental board assembly cost), or Freelance PCB Design, Quoted Job 1711777. Ragworm, PCB Shopper (comparison, can get 5 boards from China for £10). JLC PCB Manufacture (fast, economical) also PCBWay
  - Schematic Layout Software: TinyCAD (awesome: 20MB, quick, easy, no fuss, plenty of design library elements, creats PCB netlist, free) VeeCAD (stripboard editor). FreePCB (via PCB netlist export feature). Or use Spice (for simulation). WALK-THROUGH, explanation #2
  - PCB Layout Software: Autodesk Eagle (Windows Download, free for 80cm2 board), KiCAD (open source) (Windows download, 478MB to install, lite version no 3D or help PDFs), FreePCB, other free softwares. Eagle to KiCAD conversion. Eagle vs. KiCAD comparison. FreePCB (original). FreePCB2 (50MB to install!), requires Java 8 to run FreeRoute autorouter. ViewMate (Gerber file viewer). Easy EDA. TinyCAD COMPARISONS
  - SparkFun – IC basics. Soldering Basics. PCB Basics. Parts List vs. BOM Making Parts Footprints Custom Footprints Schematic Design
  - Single vs. Double Layer PCBs: Explanation, Discussion
  - “Skywiring”, Breadboards, PCBs
  NOT NEEDED – Modelling clay (£2.12 for 56g) makes a convenient third hand for soldering. Softer variety (£2.60 for 56g)See this video on soldering spliced cable to pins for how.
  
  NOT needed – bulky, slightly awkward, and, once you get good at soldering, you can use the PCB jig with quick hacks for almost everything. Litebee Gooseneck flexible hands: 2 hands with C-clamp and soft-sleeve on alligator clips to prevent scratching, £11. Litebee two arm helper is perfect. 6 arms (£26.40) is overkill. The inflexible standard cheap 2-arm helper £5 is not recommended as it has insufficient flexibility (issue!) and alligator clip jaws that are too strong and leave marks on wire being held in place.
Heat Shrink Gun & Tubing
1. Mini Heat Gun, 300W: £9.00 WARNING: Do not block heat vents on the side to make the fan quieter. They are there to to prevent excessive internal heating which can damage the heat gun. GOOD NEWS: The heat gun has automatic overheat shutoff built in. If it does not appear to work, let it cool, then try again, keeping vents clear.
2. Heat Shrink Wrap / Tubing, various sizes: 1mm for bare 22awg wire, 2mm for insulated 22awg wire £2.11 for 328pcs, assorted colors, 8 sizes (1mm, 2mm, 3mm, 4mm, 6mm, 8mm, 10mm, 14mm) Single size: 2mm diam, 1M black for 50p, 2mm diam 4M white for 73p, 2.5mm, 1m length, clear, 52p and 3.0mm, 1m length, clear, £1.66 and 3.5mm, 10m length, clear, £1.24
  2mm diameter is appropriate for bare wire. 2.5mm/3.5mm are the right diameter for insulated 22 gauge wire.
  
  To wrap larger items: calculate flat diameter and round diameter and search accordingly (Amazon: “heat shrink 80mm”, sort by: price low to high). Formula 2*flatdiam = pi*roundiam. E.g. 85mm flat = 55mm round; 57mm flat = 36mm round. 60mm flat diameter can fit 170 tie-point board with nothing on it (8.5mm thick, 35mm wide – 3 points through a circle). 77mm flat = 50mm round can fit 170 tie-point board with components and 9V battery pack (35mmx35mm square inscribed in a circle). Buy 80mm flat diameter.
3. Heat shrink tube 85mm/55mm flat/round diameter, £3.53 for 5m This is large enough to fit 170 tie-point board with attached 9V battery, components and push switch.
Hot Glue Gun & Glue Sticks (RECOMMNEDED)
1. Hot Glue gun, 100W/11mm/on-off/carrying case, £16, or 60W/11mm/on-off, £13 or 60W/11mm glue sticks/on-off, £10 w/ 50 glue sticks. Replacement glue sticks 11mm diameter, £4.50 for 50pc (9p ea.)
  Important – there are two diameters of glue sticks, 11mm and 7mm, so check size compatibility with your glue gun.
  
  Video instructions on how to use your glue gun.
Oscilloscope, Function Generator, and Logic Analyzers (RECOMMENDED for audio/advanced signal work)
JYE Tech makes low-cost entry-level equipment
1. (RECOMMENDED) Function Generator, XR2206, runs off 9VDC. Note1: Output signal is 9VDC (use LM7805 step down converter to get to 5V if want to use with 5V circuit). Note2: pass output signal through 100kR resistor to get low current signal. Lowest price: £9 fully assembled, Current price: £8, unassembled, next day, £13, fully assembled, same day or £16, fully assembled. Biggest benefit: knobs for selecting frequency, jumper for waveform (triangle, sine) with amplitude for these and specific output port for these (bottom/yellow). Criticism: (1) no power on LED (you need a meter to check its working), (2) no markings on the pots (you need a scope to know what freq is being output), (3) awful documentation – figure out by trial and error, (4) amplitude only works with triangle/sine wave not square wave, (5) has two outputs instead of one, i.e. separate dedicated dquare wave output and a separate sine/triangle output. Chip 16-pin DIP: 2pc for £4.70 (£2.37 ea) (ebay) or £7.80
  XR2206 Function Generator board documentation. Using an oscilloscope, we can see that the generated waveforms are decent (sinusoid, triangle, square).
2. Function Generator, FG-100 DDS, 1 Hz to 500 MHz, Sine/Square/Triangle/Sawtooth, £18.20 Instructions here Works, but not user friendly: to change frequency requires lot of button presses. Would prefer a knob. Power is 5VDC but has USB interface. Would prefer a standard power jack. It is useful for precisely dialed in frequencies. Requires BNC to croc clip cable.
3. Function Generator, ICL8038, £6.50 unassembled next day | fully assembled | chip only 14-pin DIP, 5pc for £13 (£2.60 ea)
4. Function Generator, AD9850 Waveform Generator
5. Desktop Function Generator, dual/multi-channel, MHS-5200A £75 | JDS6600 £107 | FY6900 £130
6. ZK-PP1 square wave PWM pulse generator: lowest cost $4.50 or current price: £12 amazon
7. Velleman MK105 Function Generator,
  
  Oscilloscopes: Buy one with rotary knobs and not buttons (cumbersome to adjust). Cheapest adequate scope with 1 channel is £35 (DSO-150). Once you start working with signals, you’ll want a 2 channel scope to be able to compare two signals on the same grid. Cheapest here is £150, so a significant step up.
8. (RECOMMENDED) Oscilloscope DSO-150: 9V DC nominal input (8-10VDC rated), 100mA (1W draw). Can run off a 9V battery. Use 9V battery box with barrel jack. £36 fully assembled next day | £27 fully assembled, 3 weeks | £50 next day | Video review of features | Written review | DOS-150 (Shell) forum by JYETech | Hackaday article (Nov 2017) | Video how to start using | Disassembly/Assembly video | Product Info page | My experience: Bought my DSO-150 fully assembled (paid c.£15 extra for this). Initially did not work. Ultimately I was able to get it working but it required taking it apart and using a YouTube assembly video: https://www.youtube.com/watch?v=TqBRi2oHvbw
  Once that was done, I needed this startup video to get it configured right for use: https://www.youtube.com/watch?v=YMrM5D4O9mI
  
  Now that it’s working, I quite like it. However, not great that it required disassembly and fiddling about to get it to work. Here were the problems and fixes:
  
  Problem 1: Sec/Div button was erratic and then stopped working. Cause & fix: looked to be poor solder joint, re-soldered.
  
  Problem 2: No signal trace at start and analog board getting very hot. Cause & fix: not exactly sure if this was a short, or dodgy connection. Fixed by adjusting analog board connection.
  
  Was able to verify operation using integrated 1kHz test signal. Works fine now.
  
  Overall Review: Easy to use, works well for testing audio (<20kHz) and other low-bandwidth, regular, signals. Lagged (not real-time) for time divisions slower than 0.2 sec/div, so not great for analysis of transients.
9. DSO-068 – £40 3 weeks, kit. Single-channel, Advantages: built-in lithium ion battery. Spec sheet
10. DSO-094 – Dual Channel Oscilloscope – Amazon | £120 NooElec
11. PicoScope 2204 – £95
12. (tried, next gen DSO-150 is better buy) DSO-138 – Digital Signal Oscilloscope (DSO), JYETech DSO138, £27, pre-assembled with BNC to croc clip cable., £19 fully assembled. This is a useful little scope upto 20kHz (audio range). Above that be aware that sampling rate limitations make this scope inaccurate, so if you are working with >20kHz frequencies, look elsewhere. Outstanding value for low frequency use (<20kHz). Easy to use (small gripe: would be better to have knobs for tuning zoom window rather than buttons). Don't bother assembling the case - it's complicated and does not add anything. Just attach the LCD unit, connect the BNC cable, power up with 9VDC wall wart, read the user guide, and off you go. Kit website
  Usage Notes:
  - Built around STM32F (ARM-CortexM3) microcontroller
  - Boots upon powerup. RESET button reboots.
  - Interfaces from left top down and around to right top:
  - CPL: Gnd, AC, DC
  - SEN: 1V, 100mV, 10mV sensitivity
  - SEN2: x5, x2, x1
  - TRIGGED led flashes green when the signal passes above voltage threshold (adjust when right arrow is blue on screen)
  - SEL: toggles through 5 functions: time period (start at 10ms), AUTO/NORM/SINGLE trigger mode (default AUTO), TRIGGER EDGE mode (rising/falling edge), 3 graph modes: right arrow blue = trigger level (put to center of signal), top window blue, left arrow blue.
  - OK: pushes hold to freeze signal
  - Then plug the red/black leads into signal (into speaker) and ground to see the waveform.
  - OVERALL REVIEW: Works fine, but it’s fiddly to use with a function select button that toggles through 5 function. Better design would use adjustment knob (rotary encoder) which is more natural – see DSO-150 for exactly this!
13. Two Channel Scopes: Hantek DSO2C10 £190 | Owan SDS1022 £190 | Kiprim DS1202 £200 | Akozon DS212 £150 or £130 3 weeks|
14. Combination oscilloscope and multimeter, £70, nice piece of kit but pricier than the £50 getting them separately.
15. BNC croc clips test cable, 2pc for £4 (£2 ea.)
16. Tektronix 465B – the analog standard
17. Combination Oscilloscope & Signal Generator: £143 | £240 | £85. Note – it is often better to get standalone equipment so they can be upgraded separately when more is needed for that particular function.
18. Logic Analyzer, £100
Assortment of Craft Tools/Misc. (OPTIONAL)

B. Components & Supplies

Solderless Breadboards (2.54mm pitch). When not to use breadboards.
Features to consider: (1) Power rails down the side of the board (on 400+ tie points), (2) Attach/detach modularity (on 400+ tie points), (3) Central spacer for ICs (keeps pins separate on either side) (170+ tie points), (4) Two columns of horizontally connected rows (170+ tie points)

Use with 22-AWG hookup wire. Using thicker wire (20 awg or lower) can spread the clips apart for the whole row and cause loss of contact with smaller gauge wire

Fully modular means they can be clipped together horizontally or vertically to extend them. The power rails can be also unclipped to create double wide dimensions. Note the 170 tie point boards have just 1 modular clip per side which is not enough for mechanical stability without another strength member.)
1. Large: 1660 tie points: ZY-204, £11 next day, Vellemen VTBB4, £17. 2860 tie points: £11.20
2. Tall (MB102): 830 tie-points 4 power rails – £3 ea or
3. Medium: 400 tie points, w/ IC divider and 4 power rails: Lowest: £1.16ea, Currently: £1.70ea (MOQ6) or £1.67ea (MOQ6) or 3pc for £6.30 (£2.09 ea.) or 3pc for £7 (£2.33 ea).
4. Small: 170 tie points, w/ IC divider but no power rail: lowest price 36p ea. 5pc for £1.98 (40p ea) white with interconnect nubs, Ebay. | These were defective, requiring too much force to insert pins. Refunded.
  Excellent for little portable projects and preserving your prototyped circuits cheaply!. These are the smallest breadboards that can accomodate an IC chip because they have a DIP ravine electrically separating pins on either side of the chip.
5. Tiny (ZY-55): 55 tie points, no power rail: 7x for £4.80 (68p ea) ebay or 7pc for £3.69 (53p ea.)
6. ZY-001 baseboard: Red, £2.59 ea., Yellow, £2.59 ea., White, £2.69 ea
  The ZY series are excellent for little connections that don’t require ICs. The little nubbins on the back of the ZY series breadboards are like little lego attachments made to fit the ZY-55, ZY-35, and ZY-25 modules. NOTE: the spacing on the ZY series boards are not compatible with LEGO spacing — a pity!. Also note: The smallest breadboard (ZY-25) with 25 tie points 7pc for £2.70 (40p ea.) is not recommended and is not child-friendly, as the 5-rows and 5-columns mean there is no easy way to know which set of 5 holes are electrically connected, rows or columns. Stick with ZY-35 or ZY-55.
  
  References:
Prototype PCB for point-to-point wiring
2.54mm pitch same as breadboards aka Matrix PCB, Protoboard, Universal PCB, Paper PCB Check Amazon and Ebay for better prices.
vs. stripboard or Veroboard with interconnected strips like a breadboard.
Look for pre-drilled corner holes for nylon standoffs (most are M2, with single-sided paper PCB can expand to M3 with a drill).

Two types: single-sided phenolic, paper PCB DON’T BUY THESE TYPE: bad smelling, can’t take much heat before pads lift off. Better to buy these slightly more expensive: double-sided FR-4 fiberglass boards with tinned pads: higher quality, thicker boards, able to handle desoldering and resoldering. (Double-sided helps wire routing for more denser layouts). Thickness matters more for larger boards, where 1.6mm (paper PCB) may be too thin as there is greater flex in the center, especially if using heavier components, or pressing buttons, which can cause pcb joint failure.

Standard PCB sizes (cm): Small: 2×8, 3×7, 4×6, *5×7, 6×8, *7×9 (like 400-tie point breadboard); Medium: *9×15 (wider version of 800-tie point breadboard); Large: *10×22 (useful), 12×18, 15×18; Extra Large: 13×25, 18×30 (almost A4). (recommend to get 5 pc ea of 5×7, 7×9, 9×15, 12×18)
1. Small PCBs (7x9cm or smaller): Best value is 40pc kit for £12 (30p ea) + storage box, same day contains 2x8cm (10pc), 3x7cm (10pc), 4x6cm (8pc), 5x7cm (8pc), 6x8cm (2pc), 7x9cm (2pc). Other sets: 32pc for £11 same day, 16pc for £5 (31p ea), fewer sizes, 1 week, or 20pc for £10 (50p ea), same day, or 20pc for £10 (50p ea), more sizes, 3 weeks
  3x7cm: 10pc for £5.23 (52p ea) next day
  4x6cm (FR-4, 2-sided): 4×6 cm, 10pc for £5.80 (58p ea), next day, or 10pc for £6.50 (65p ea), same day
  
  5x7cm (FR-4, 2-sided): 10pc for £4.90 (49p ea) 30 days
  
  5x10cm (FR-4, NOTE one-sided NOT two-sided): 2pc for £4.67 (£2.33 ea) NOTE: This is a single-sided board. If you need the form factor, better to get the Electrocookie snappable (below).
  
  6x8cm (FR-4, 2-sided): lowest price: 86p ea.
  
  7x9cm (FR-4, 2-sided): 5pc for £4.50 (90p ea)
2. Medium PCBs (bigger than 7x9cm): 2-sided FR-4
  8x12cm (FR-4, 2-sided): 2pc for £3.40 (£1.70 ea) or 2pc for £4.38 three-day (£2.19 ea) or 10pc for £13.31 (£1.33ea)
  
  9x15cm (FR-4, 2-sided): 5pc for £6.16 (£1.23ea) or 2pc for £4.66 three-day (£2.33 ea) or 2pc for £5 (£2.50 ea) or 10pc for £18 (£1.80 ea) same day
  
  10x15cm (FR-4, 2-sided): 10pc for £25 (£2.50 ea) next day
  
  12x18cm (FR-4, 2-sided): 1pc for £3.28 (ebay)
  
  15x20cm (FR-4, 2-sided): 5pc for £27 (£5.40 ea) or 1pc for £10 or 1pc for £7 three-day (ebay)
  
  10x22cm (FR-4, 2-sided): 2pc for £9.20 (£4.60 ea), 1pc for £5.50 or 2pc for 15.60 (£7.80 ea), 1pc for £8.20
  
  13x25cm
  
  18x30cm/20x30cm (FR-4, 2-sided): £9 ea (MOQ2) 3 days or £9.20 ea (MOQ2) 4-6 wks
3. Electrocookie, snappable solder PCBs with solderless interconnections, for permanent fast prototypes, 9.7×8.9cm 6pcs 9.7 x 8.9cm, or 24 pcs 4.85cm x 4.45cm, £18 (£3 ea large, or 75p ea small), or 3pcs for £12 (£4 ea large, or £1 ea small) Excellent PCB when connecting many small components/ICs, reducing the number of solder bridges that need to be built.
4. Bendable PCB, 15x-18cm: 2pcs for £34 (£17 ea)
Nylon Hex Stand-offs / Board Spacers
1. Female 100pc Black Nylon 8mm M3 spacer, £1.86 (2p ea), 3 days or 5mm 100 pc for £1.99 (2p ea.)
2. Male 100pc Black Nylon M3 spacer (tall, 12mm+6mm), £3.01 (3p ea) (lowest price 2p ea) or (short, 6mm+6mm)
3. M3 (3mm hole) nylon screws 20mm height black, 50pc for £3.41 (6.8p ea) or 8mm height, 50 pc for 70p (1.5p ea), or 30mm height metal 8pc for 89p (11p ea), or 22mm height metal 20 pc for £5.49 (27p ea) next day
4. M2 Nylon spacer/standoffs Hex, Universal Standoff Ordering — all sizes and combinations! 4-5p ea buy: M2 black 100pc M/F 8/6mm and M2 black 100pc F/F 6mm (200pc for £9, 4.5p ea) (note, base length must be bigger than screw for securing PCB)
Wires / Wiring
Reference: Choosing wiring gauge (thickness, max current, resistance)

Reference: Wire gauge to mm conversion chart (e.g. 22-gauage = 0.6mm) and making sense of European wire measurements (e.g. 16/0.2mm and 24/0.2mm means 16/24 strands of 0.2mm diameter wire; solid core wire is 1/X)

Reference: Working with Wire – Sparkfun Tutorial | AWG to mm converter
1. Hookup wire, 22-gauge (0.6mm) single core , red (positive), blue (negative), yellow (signal), 5m spools. Add orange and violet for additional colors. This is the stuff for making short jumper wires for breadboard connections.
  Thin wire for prototype PCB boards: Note 22 AWG wire is 0.6mm, 28 AWG is 0.3mm, 30 AWG is wire wrap wire 0.25mm. Cellphones use 0.1mm wire (38 AWG). Thinnest is 40 AWG at 0.08mm
2. Magnet wire (0.2mm, #32 gauge), Red, £2 for 100m
3. Wire wrap wire (30 AWG), £4 for 8 colors, 15m each (Only downside is they are all wrapped together. Would prefer each color spooled separately).
  With wire wrap wire can do point-to-point soldering by attaching to the pins of an IC. No longer need the harder work with thin (0.1mm) copper enameled winding wire, 5 pc (15m long ea) for £4.70 (6p/m) same day, directly solderable without scraping off insulation. DON’T use magnet wire which whose insulation is gives off toxic fumes and cannot be directly soldered.
  
  How to Solder Tiny Things, example of wiring using copper winding wire, or here. Step-by-step here.
  
  Extreme Soldering (highly recommended to learn advanced techniques) | Examples of Point-to-point soldering on Protoboard PCB using Wire Wrap wires | To use wire wrap wire you will need a nice pair of tweezers.
4. Stranded flexible wire, 22-gauge, £1.81 in 2018 (red/black each for 3m, so 30p/m), £1.26 in 2016 or ebay at £4.50/10m red and black or 45p/m
  This comes in handy when creating leads for items you’ll want to move around flexibly, e.g. switches, or potentiometers that are user interface items, vs. inflexible hookup wire.
5. Jumper Wires (compatible with standard breadboard with 2.54mm pitch/0.1″ sockets):
  ProTip: Choose F/F wires and long header pins which can be used as grouping organizers (multiple cables), or gender changers.
  (short) 10cm: £2.75 for 40pc.
  (medium) 20cm: MM/MF/FF mixed kit purchase – Lowest price: 1.3p ea., current price: 3.2p ea (MOQ400) or 4.8p ea or 360pc for £9 (2.5p ea, 120 pcs each type)
  
  These are useful for connecting between boards, whether breadboards, PCBs, or microcontroller dev boards (flexible, reasonable size, come prefinished in variety of terminations.
6. Jumper Cap Connector / Short Circuit Shunts (2.54mm pitch):
  With handle: 100pc black for £3.30 (3p ea) or 10 pc black for £3.25 (32p ea), or 10pc black for £3.86 (39p ea), or 60pc tri-color for £8 (13p ea), next day, or 200pc 4-color for £10 (5p ea) next day
  
  Cheaper, but require pliers to add/remove: 120 pcs for 97p (black) or 50 pcs for £1.16 (black) or 10 pcs for 63p (6p ea), blue
  
  Jumpers are essentially single-pole N-throw switches (1PNT) that you build manually to fit your application. Very convenient and cost effective when considering expensive switches. All you need are header pins and the jumper shunts. The rest is wiring.
7. Magnet wire (0.2mm, #32 gauge), Red, £2 for 100m
  Useful for wiring inductors of 1mH or higher.
8. Wiring inter-connection kit (Male/Female Crimp Pins, Female Header Blocks), 620 pc, £4.57
9. 2.54mm pin header strip (male) 10 pcs of 40 pins, 77p and 2.54mm pin header strip (female) 10 pcs of 40 pins, £1.27; or get both for 1.70.
10. Right-angle male header pins 2.54mm spacing, 40 pins per row: 30 rows for £4.36 (14p ea) *important* must have nub on the wire pin allowing flush pcb mount, not on the pcb pin which leaves a gap in height above board | 12pc for £6.00 (50p ea row) nub on wire pin
11. Double-long 8mm/8mm straight male header pins 40 pins per row, 10pc (40 pins ea) for £9 (90p per 40-pin pc) next day or 1pc (40 pins) for £1.42 (@MOQ2) 3-days, ebay,
  Note: typical male header pins have a needle length of 6mm on the connect side, and 3mm on the PCB side. These are 7.6mm on each side, so can be inserted easily into a solderless breadboard.
  
  Instructions for:
  
  Connector Basics: Everything you ever wanted to know about all possible connector types (Sparkfun)”
  wiring female connector block
  (video) how to use the male crimp pin
  (video) soldering pin headers and pins to boards using a breadboard as third hand
  (video) soldering technique to solder spliced cable to pins using modelling clay as third hand
  (video) using a d-sub crimper to crimp wire
Connectors
1. 2.1mm DC Barrel Jack / Barrel Plug / DC Power Pigtail Cable Male: Center positive: lowest price 19p ea., 20 pc for £6.00 (30pc ea), or ebay 10 pc. for £3.50 (35p ea). or with
  Amazon 10 pc for £2.93 (29p ea.), or 10 pc for £5 (50p each)
2. 2.1mm DC Barrel Socket: lowest price: 7.5p ea (10pc for 75p), or currently: £1.89 for 10 pc (19c ea.) WARNING: these are open mouthed (Ebay) to get them to insert into a standard breadboard pull out the middle pin with pliers, or 10 pc for £1.82 (18p ea), Ebay, or £1.66 for 5 pc (33p ea)
  These are fantastic and great also for general electronics repair or hacking into DC devices by splicing into power cable or battery terminals
3. IDC connectors, Ribbon Cable, and Board Headers, 10- to 50-way (Spiratronics). Installing Ribbon cables – demonstration, instruction. (IDC = Insulation Displacement Cables). Ribbon cables (Amazon)
4. IDC ribbon cables: 6-pin female for SPI / ICSP programming of Arduino, 5pc for £6 (£1.20 ea) 20cm next day, 20-pin female, 5pc for £8 (£1.60 ea) 30cm next day
5. Model & RC connectors (small molex)
6. 12VDC Car cigarette lighter FEMALE socket to wire terminals, £10 for 2
7. Power Inverter: 120/240V AC to 12V DC (10A) compatible with a car DC cigarette lighter connection. £20
  But first look amongst old computer power supplies you may have lying around.
8. Screw Terminal Block Connector for PCB: 2-pin terminal 40 pcs for £1.84 (5p ea.)
  These are bread-board or PCB compatible, and can be stacked to make 4-pin, 6-pin, 8-pin, connectors (a small tab on one side and a slot in the other creates the inter-connect)
9. Wire connectors (twist on), wire nut
10. Spring wire connector
LEDs
1. Standard LEDs come in two sizes: small=3mm, medium=5mm, but can be up to 10mm (large)
2. Note: Different LED colors have different forward voltages hence different brightnesses. Forward voltage (see table below) for most colors is 1.7-2.3V, with 3.2V for blue & white LEDs (super bright).
3. Tip: To get even brightness LEDs of different colors, use different resistor values. On 5V, try: Green: 33R, Yellow: 1.5KR, Red: 5.2KR, Blue: 20KR, White super-bright: 22KR
4. Tip: Why old stock green LEDs are much dimmer. “There are two types of green LEDs. Old green LEDs with forward voltage ~2V which are quite poor – the brightness @20mA is comparable to red LEDs @2mA. Also yellow LEDs are often poor. New green LEDs have forward voltage ~3.5V and are much brighter – about the same as blue and white LEDs, more than the red LEDs. Before the ’90’s most LEDs were extremely low brightness (about 1000 times less than today’s types). Check the forward voltage to be sure you are not getting old stock dumped. Source
5. Tip: Modern red LEDs light up at 1mA (5V, 5mW), shine nicely at 2mA and brightly at 4mA. So at 5V, a 2KR resistor is plenty fine.
6. Max forward current is 20mA. Protection with 1KR is enough for 3-12V (3-12mA), not including fwd voltage, which removes another 2-3mA. At 5V, 250R gives max allowable current (20mA). At 9V, 480R gives max allowable current.
7. Simplest circuit is driven by 9V battery with 1k ohm resistor, so resulting voltage is 6V (after LEDs forward voltage), so current will be 6mA. These are bright 3V DC 3mm diameter LEDs, perfect for DIY electronics. Easy to test with a test circuit in a few minutes (9V battery, 1 LED, 1k ohm resistor) using breadboard (but could also use test leads).
8. LEDs have polarity which is indicated with + being the longer leg. Brightness can be adjusted by lowering the resistor value (but be careful not to pass more than 20mA through the LED lest you burn it out, so min resistor is 330 ohms for max brightness, or 470 ohms to be safe).
9. LEDs come in two current types: std and low current. Low current LEDs provide uniform luminosity down to 2mA unlike standard LEDs whose luminosity decreases with current, but which are still reasonably bright down to 2mA. But low current LEDs are 10x more expensive at c.15p ea (vs. 1.5p std current) and appear to only be available in 3 colors for low-current LEDs: Red, Green, Yellow from Kingbright
LED forward voltage chart (courtesy of: http://stompville.co.uk/?p=37)
1. 3mm (std small) Size. | 5x color kit (white, yellow, red, green, blue): 750 for £10 (1.33p ea) next day, with 15 compartment box, 150pcs each color, | Consider single color packs
2. 5mm (large) size | 5x color kit (white, yellow, red, green, blue): £4.89 for 100pc, 20 each color.
3. Small Low-Current: Kingbright 3mm, £3.50 (incl. S&H) for 25pc (14p ea).
4. Large Low-Current: 5mm, £2.62 for 10pc (26p ea.) (Spiratronics on Ebay)
  Note – the multi-colored special LEDs are auto-flashing, and make great wearable Christmas jumper LEDs
5. LED holders are sized to match: 3mm LED holder, 50 pc. £1.17, larger size: 5mm LED holder clip panel, 50p for 50 pc.
  1. **KY-009 – RGB 3 color SMD LED module aka Colour Mixer (4-pins), recommended for colored lighting work, as these have a very nice integrated miniature lightpipe in which the colors get mixed, to produce one color output.
  2. KY-016 – RGB 3 color LED module (4-pins)
  3. KY-011 – Dual Color (Red/Green) LED Module, £5.40
  4. KY-034 – 7-color Auto Flashing LED module
6. Addressable LED strips (able to light any pixel with any color) – software control, SK6812 (RGBW) & variants – Products: 1m strip IP67 144 leds/m, SK6812, £22 6 weeks or £36 same day, or £25 for 10×10 matrix (100 LEDs)
7. Lens for Flashlights. Flashlight enthusiasts | Projection Flashlight | £5 Wilko Halloween Projection Flashlight with 5 lenses, or £0.50 direct from Wilko
Resistors & Potentiometers
1. Resistors are rated by power dissipation. Standard are 1/4W. Then you have 1/2W, 0.6W. Then the high power applications 1W+ rated.
2. Resistors are rated by tolerance. Standard carbon film (cream body) are 5% tolerance. Precision metal film (blue body) are 1% tolerance.
3. Resistors in series add rating.
4. You don’t need every value. These 3 values are the most needed: 1K (good for LEDs, get 50x), 10K (good for pullups, get 50x), 100k (good for audio signal mixing, get 50x), These 12 values are a sensible assortment: 100R (protects switches against surge capacitors, get 20x), For LED brightnesses: 33R, 220R, 470R, 1.5K, 2K, 5.2K, 20K- get 20x each. For high resistance, get 1M, 2M, 5M, 10M – get 10x each. The rest of the values are useful when creating e.g. precise frequencies for oscillations (using RC circuits/transistors, or 555 timer ICs).
5. Most digital electronics is low power. Fresh 9V DC battery (9.45V measured) with 470R resistor produces ~20mA current or 180-200mW of power. The resistor will get quite hot to the touch but can endure this without damage.
6. What happens if you increase power above the rating of the current limiting resistor? Doubling the power with a 220R (45mA current, 425mW power) gets the resistor burning hot to touch. Doubling again to 100R (90mA current, 800mW power) will literally smoke the resistor.
7. Bottleneck components: Resistors (standard 1/4W, but can go up to 6W rated), Transistors (2N2222 are rated at 1A but get hot at 650mA, can step up to TIP122 Darlington at 5A), 22 gauge single-strand hookup wire rated at 7A (XmA hot / xmA melt)
  For audio applications, keep in mind that speakers are often 8R, so no point in going below this if the desire is to maximize current (just remove the resistor and use speaker resistance alone).
8. Higher power resistors allow measuring higher currents through a circuit. Don’t forget that 22AWG also have a max rating of ~5A after which they will melt. Your multimeter likely also has a 10A fuse which will blow if you try to mass more current through.
9. High currents can be generated by shorting a 9V DC battery or 2x9V DC batteries in parallel. But be careful, either use a reliable fuse, or keep the flow time very small (1 sec max). More will make the battery burning hot and melt the wire harness. Wear safety goggles if you try this!
Resistor color chart for standard precision (5-10%, 4-color bands, tan body) and high precision (1%, 5-color band, blue body) varieties
1. Resistor Assortment Kit low power 1/4W (250mW) rated
  1. Standard 5% tolerance carbon film (cream body): 75 values x 20 pc. ea, 5% tolerance. Values: Ohms: 1R, 2R2, 4R7, 5R6, 7R5, 8R2, 10R, 15R, 22R, 27R, 33R, 39R, 47R, 56R, 68R, 75R, 82R, 100R, 120R, 150R, 180R, 200R , 220R, 270R, 330R, 390R, 470R , 510R, 680R, 820R
    Kohms: 1K, 1K5, 2K, 2K2, 3K, 3K3, 3K9, 4K7, 5K1, 5K6, 6K8, 7K5, 8K2, 10K, 15K, 20K ,22K, 33K, 39K, 47K, 51K, 56K, 68K, 75K, 82K, 100K, 120K, 150K, 180K, 200K, 220K, 300K, 330K, 470K, 510K, 560K, 680K, 750K
    Mohms: 1M, 1M5, 2M, 3M3, 4M7, 5M6, 10M. Get the 75 value pack and then replenishment commonly used resistors individually (1K, 10K). These arrive in neatly labelled sheets of resistors.
  2. Low 1% tolerance metal film (blue body): Resistor Kit, 600 pc. for £3 (0.5p ea.), 30 values x 20 pc. ea (10R to 10M-ohm), 1% tolerance Values: 10R, 22R, 47R, 100R, 150R, 200R, 220R, 270R, 330R, 470R, 510R, 680R, 1KR, 2KR, 2.2KR, 3.3KR, 4.7KR, 5.1KR, 6.8KR, 10KR, 20KR, 47KR, 51KR, 68KR, 100KR, 220KR, 300KR, 470KR, 680KR, 1MR
  3. Can be more more cost effective to get particular values: 1K, 10K, (common) 680R, 820R (substitutes)
  4. Bulk specific values: 10KR 500pc for £7.35 (1.5p ea) or 100pc for £2.80 (2.8p ea) | 1KR 100pc for £4.00 | 680R 100pc for £2 (2p ea), 5 days or £4.44 (4.4p ea) next day
2. Resistors for high power/high current applications. P= VI = V^2/R.
  1. 1000 pcs 1/2W (500mW) rated carbon film resistors, clustered around low Ohm ratings, £20 Spiratronics
    Best value – power resistors, assortment, hand selected, 35 pcs for £8.25 (23p ea), 1/2W, 1W, 2W, 3W, and 6W resistors, from 5R to 200R
  2. 10-pack sheets 1/2W fixed value resistors: 10pc for 44p, individual values choose *100R (for 1/4W draw @ 5V), 56R (450mW draw @5V), 33R (750mW draw @5V),
  3. 1W metal film resistors, 16p ea. MOQ5, individual fixed values, get 100R, *33R (450mW draw @5V), 22R (1.14W draw @ 5V)
  4. 2W metal film resistors, 11p ea. MOQ5, individual fixed values, get 33R (5 ea)
  5. 3W metal film resistors, 19p ea. MOQ5, individual fixed values, get 22R (1.14W draw @5V), 10R (2.5W draw @5V), (5 ea), allows up to 600mA at 5VDC
  6. 6W wire wound resistors, 73p ea., individual fixed values, get 5R (2 pc), 150R (2pc), allows up to 1.2A at 5VDC.
  7. 150R, 1W, 10 for £1.97 (20p ea.)
  8. 10R, 10W, £1.02
  9. 1R, 100W, £1.37
3. Trimmer pots, single turn screw. Box kits with many values:
  Once you have prototyped your circuit with the screwdriver adjustable trimmer pots, then you can select the specific 6mm shaft diameter potentiometers with the right values and in the right quantity, either with rotary control knob, or separately. Article1 Article2
4. Potentiometer shaft diameter 6mm:
  Two types of potentiometers (pots) linear (B-taper) or logarithmic (audio, A-taper, or C-taper for reverse log) based on how the resistance varies as you turn the shaft. Audio (A-taper) pots are typically used for volume control since the human ear perceives loudness according to a logarithmic (dB) scale, so A-taper pots are perceived to vary volume uniformly throughout their range. B-taper (linear) pots will deliver what seems like 100% of the volume change within 5% of the pot range. Article 1 (with graphs), Article 2, Article 3.
  PCB pots are preferable for precise knob control– the chassis mounted pots have a phenolic pcb base which is heat-sensitive and prone to dodgy solder joint connections.
  
  PCB Pots – A (audio, logarithmic) taper
  BEST VALUE: Taiwan Alpha Breadboard/PCB pots with right-angle insertion and knurled shaft:
  All values – RV09 10k 4pc for £6 (£1.50 ea).
  Next best – some values
  Kit of 22pc for £32 (£1.48 ea): Values: 4x1K, 2x2K, 4x10K, 2x50K, 4x100K, 2x500k, 4x1M
  Knobs for this shaft (£1.75-2.75 ea)
  
  PCB Pots RV09 – B (linear) taper
  Most flexibility: any value, any taper, 10pc for £3.50 (35p ea), 10pc for £3.00 (30p ea), 100pc for 14.20 (14p ea)
  BEST VALUE: Ascot City/Sourcing Map Breadboard/PCB pots with right-angle insertion and knurled shaft:
  9 values, 5 each, £10.50 for 45 pcs (23p ea), 1K, 2K, 5K, 10K, 20K, 50K, 100K, 200K, 500K, 1M
  BEST VALUE: Any value, any taper, 10pc for £3.50
  10K: 10 pc for £6.50 (65p ea) next day
  100K: 10 pc for £6.00 (60p ea) next day
  1M: 10pc for £5.20 (52p ea) next day
  
  Linear Pots (B Taper)
  
  B1K, 10K, 100K, 200K, 1M ohm linear taper: Small values kit £7.88
  £5.15 for 5 pc (£1.03p ea.)
  
  Audio Pots (A-Taper, Logarithmic taper), A10K 60mm SLIDER pots. Wiring detail
  
  Cylindrical PCB mountable (but not breadboardable)
  A1K – log (A) taper – 5pc for £2.75 (53p ea) or 5pc for £2.75 (53p ea) dual pins These A1K 6mm pots work great and deliver smooth audio response.
  My preference would have been for pins instead of solder lugs in order to use them directly for PCB/breadboard insertion, but this is stated in the description, and for the price it’s easy enough to workaround (solder hookup wire to the lugs). These comfortably handled measured 3W of power (2A at 1.5V in circuit measurement, powered by 5V DC wallwart). In tolerance test, they began to overheat at 11W of power (3.8A @ 3.0V, powered by 9V DC wallwart), and continued working for extended duration when 3W power restored.
  
  A10K – log (A) taper – 2 pc for £2.50 (£1.25 ea)
  A20K – log (A) taper – 2pc for £2.68 (£1.34 ea)
  A50K – log (A) taper – 2pc for £2.48 (1.24 ea)
  A200K – log (A) taper – 2pc for £2.48 (£1.24 ea)
  A500K – log (A) taper 10x 500K-ohm for £4.00 (40p ea.)
  
  Wiring – three circuit designs, two distinct choices: variable resistor (rheostat) or voltage divider (potentiometer). Both choices use the same hardware, which has a twist pole (6mm typical) and three pins so you can choose which direction you want the increasing resistance.
5. Rotary control knobs for Trimmer potentiometers 6mm shaft diameter:
  - Black w/ colored top and stripe, Black with stripe. Colours are white, red, blue, yellow, orange
  - Silver metallic dials, 5 pc. for £1.42 (18p ea.)
  - Red, with lettering “Volumex1, Tonex2”, £1.42 for 3pc. (42p ea)
  - Calibrated Knobs 4pc for £6 (£1.50 ea), 18pcs for £9 (50p ea)
Capacitors (1uF = 1k nf = 1m pf, so 0.1uf = 100k pf)
Two types: Electrolytic (cylinder) with polarity and Ceramic (disc) without polarity. For electronics work, get 16V rated caps (not 50V rated) to reduce physical bulkiness. Intermediate values can be reached by summing the value of capacitors wired in parallel.

Applications: (1) Smoothing capacitors reduce voltage ripple in a power supply, (2) Decoupling capacitors stabilize voltage against spikes and drops, (3) RC capacitors providing charge/discharge timing, e.g. for oscillators, (4) Coupling capacitors block low frequency DC and allow higher frequency AC to pass, e.g. in amplifier circuits for speakers.

Decoupling/Smoothing/Bypass capacitors (Wikipedia) reduce voltage ripple from a power supply, from 0.1uF (#104) to 10uF (to smooth a 30mV ripple) on up, observable on a scope, or calculated through an equation

Notes:
Capacitors voltage is often either 16V/25V/50V. No need for bigger 50V. 16V is fine. But higher does no harm.
1. Large (>470uF)
2. Medium Electrolytics (470uF-1uF, less than 1s charge time) from 1uF to 2200uF.
3. Lowest price: 120pc for £1.43 (1p ea). @25v/16v: 2200uF, 1000uF, 680uF, 470uF, 330uF, 220uF, 100uF, 47uF , 33uF, 22uF*, 10uF, 4.7uF, 3.3uF, 2.2uF, 1uF. Currently: 300pc for £8 (2.6p ea) 15 values, 20x each up to 470uF with storage case (next day).
4. Small Ceramics / Electrolytics Kit: 1000 pcs for £4 (0.4p ea.), 50 values (1pf-100nf=100kpf) x 20 pcs ea.
5. To replenish individual values, it is cheaper to buy 10-packs from Spiratronics and pay the £1.25 2-day shipping:
  100uF / 10V at 40p for 10 (4p ea)
  10uF/16V, 6p ea (MOQ10)
  100nf and below (Spiratronics)
  47nF = 47k pf = #473 10pc 26p
  10nF = 10k pf = #103 10pc. 26p
6. Custom value ceramic capacitors:
  10uF – smoothing capacitors for power supplies/batteries
  0.1uF = 100k pF (#104) – smoothing capacitors per IC – 100nF = 100K pf = 0.1uF = #104 10pc. for 26p (2.6p ea) or 100 pc for £3 (3p ea)
  22pF – pair of capacitors for 16MHz crystal oscillator, for use with Atmega328P standalone with standard bootloader fused for 16MHz external clock. 10pc for 31p (3p ea)
  3.3 uF capacitors, 30pc. for £1.25 (4p ea.)
  330nF (=0.33uF) 25 pc. £3.64. This is an important value for 9V to 5V DC to DC regulators, and is slightly more convenient than choosing 220nf + 104nf (324 equivalent capacitance).
7. Trimmer Capacitors 45 pc. for £5.00 (11p ea.), 5pF to 120pF, 9 values x 5 pc. ea.
Transistors are electronic switches which consume a forward voltage drop. Two types, BJTs (collector, base, emitter), and FETs (source, base, drain), each of N and P types. NPN is normally off and a current to the base turns it on; PNP is normally on and current to the base turns it off. Choose based on max rated current, gain, and max switching frequency.
- Max rated current: TIP3055 (Darlington array) upto 15A, TIP122 (Darlington) upto 5A, 2N2222 upto 1A, 2N4401 to 600ma, and 12N3904 to 100mA
- Signal frequency considerations (e.g. in audio or radio applications).
- RTL logic inverter application.
- SPST, SPDT, and DPDT switches
- RC oscillator circuit using caps
- variable current production by lowering the current through the base well below the saturation point of the transistor (ie where the gain must fall below max rated gain because the circuit limits the flow). E.g. a 5V circuit with 1K resistor and yellow LED, this means using between 100K and 1M resistors on the base signal. Anything smaller resistance, and you’re essentially saturing the transistor anyway.
1. 2N2222 Transistor (Amplifier), NPN (normally open)-type, 100 pcs for £1.59 (<2p ea.), forward voltage drop 0.7V, current gain 100x hFe, max current 1A , Component Notes and Pin Diagram
  
  2N2222 Transistor, 600mA rated, With flat side to the right, collector leg is on top.
  
  Darlington transistor arrays can be obtained in an IC package (ULN2003A) as they are common in stepper motor driver applications.
2. TIP122 Darlington transistor TIP122, rated to 5A, forward voltage drop 1.4V, 10pc for 1.08 (18p ea) Component notes and pin diagram
  PUT (programmable unijunction transistor) offers another approach to building oscillator circuit, with fewer components.
3. 2N6027, 10pc for £6 (0.60 ea) Datasheet: 2N6027 datasheet
4. B521 MPF102 Transistor £2.63 for 10 pc. (26p ea.) for use with LM386 Audio Amplifer chip.
Inductors Understanding inductor parameters SMD Inductor packages are specified by a max plane dimension and height, e.g. CD54 is 5mm max width/length and 4mm height, CD43 is 4mm width/3mm height, CD103 is 10mm width/3mm height. Inductance is indicated by standard electronic terminology for resistors, capacitors, inductors, e.g. #470 means 47uH, #101 means 100uH, #4R7 means 4.7uH.
1. Inductor Cores: Green Toroid Ferrite Cores: 10mm x 6mm x 5mm, 79p for 10pc (8p ea)
2. CD54 series SMD power inductor wire wound chip, various values, 5pc for £2.77 (55p ea.)
3. CDXX series SMD power inductor wire wound chip, various values and formats, 50pc. for £2.50 (5p ea)
4. CD43 series
5. CD75 series
PHYSICAL USER INTERFACE DESIGN OPTIONS:
1. LEDs: When only binary (on/off) input is needed
2. Display: OLED display (I2C comms) – 2 pins. Or TFT display (color). When linguistic information is needed.
3. Switch: More than 4 way switch becomes clunky – (4 pins)
4. Buttons: More than 6 buttons becomes clunky (use a shift register to reduce to 3 pins)
5. Rotary Encoder: When have between 5 and 15 choices
6. Rotary Encoder with Coarse & Fine Grain selection: when have between 10 and 100 choices
7. 12-key Keypad (10+2) & 4-way selector switch: when have up to 48 choices
8. 16-key Keypad (4×4) & 4-way selector switch: when have up to 64 direct driven choices
9. 16-key Keypad (4×4) & 4-way encoded switch: when have up to 256 choices
10. Larger Keypad
11. Macro Keypad: Hackaday 18 concepts, 51 more and a few more (413) | stream deck | bluetooth with ESP32 | shortcut keypad | full tiny keypad for under $5 using CH552 uc
Switches
1. EXCELLENT: Momentary push-button tactile switch, normally open, SPST, momentary, non-latching: 2-pin, 100pc for £4.49, or 4-pin, 100pc for £4.49 (4.5p ea). Notes: Long 5.5mm pins better for breadboarding. Button height 5mm preferred to 4.5 or 4.3mm. 9mm can have button caps 6x6x9mm with caps (£10 for 50 pc (20p ea). 4 pins preferable to 2 pins (2-pins are mechanically unstable and hard pushing breaks solder joints on PCB or removes from breadboard). Better to have 4-pin variety. These buttons make a clicking sound when pressed.
  Momentary on switches (non-latching) that let current flow when pressed down. Other type is normally closed.
2. Conductive Silicone soundless tactile button, 4-pin or 2-pin DIP, 20pc for £3.50 (18p ea)
  Debouncing switches is a fine art. Jack Ganssle’s excellent white paper (PDF). using software – excellent discussion of mechanical bouncing. Summary: Sample twice 10ms apart (1ms is typical bounce period, 10ms to be safe) and check to see that the value has settled, then act.
3. Caps for 6x6x5mm Tactile switches. 55pc for £2 (4p ea)
4. EXCELLENT: Micro limit switch SW158, markings on pins: Common (C) closest to hinge, then normally open (NO ), then normally closed (NC). Lowest price: 13p ea (60pc for £8 next day) | Current price: 20 pc. for £3 (15p ea), prime. EXCELLENT for low-force repeatably reliable pressing, e.g. for piano keys.
5. Latching Push-Button Switch. 2-pole OFF/ON – Assorted buttons, select individually, 50pc for £8.60 (17p ea). Or individually: KAN112D black 2-pin 10pc for £2.15 (22p ea), KAN1208D black/white 2-pin 10pc for £2.10 (21p ea), KAN1288BM black/white, Ultra-Thin 12*12*9.4, ebay or red button 2-pin 5pc for £2.72 (54p ea) or Red 5pc. for £1.51 (30p ea.), 2-pin or Black 5pc. for £1.91 (38p ea) 2 vertical pins 3-pole OFF/LEFT/RIGHT Black 5 pc. for £1.71 (34p ea.) 3-poles OFF/LEFT/RIGHT 3-pins right angles 3-pole OFF/ONE/BOTH 4-pins Red 3-poles OFF/LEFT/RIGHT or OFF/ONE/BOTH 4-pins, 10pc. for £2.22 (22p ea)
6. Latching Tactile Switch. 9 pcs DPST for £1.09 (12p ea.) with DIP-6 pins or 25 pcs DPST for £3.11 (12p ea.) DIP-6 pins.
  Note: there are SPST switches with 3 pins on the same side for half price (6p ea) but would recommend to avoid these. While the pins make them breadboardable, the asymmetric location (all 3 pins on the same side) and the fact that the pins are a bit short, means that these switches tend to pop out at the slightest disturbance. Remedies (none ideal) (a) hot glue in place (b) solder some hookup wire to the pins to lengthen them; (c) use panel mount buttons instead and mount elsewhere with jumper wires or cable, (d) use DIP switch instead, (e) use a bit of BluTac when seating them; (f) jam in one of their pins into sharing a hole with the other in-feed wire to tightens the fit; (g) use DPST switches (twice as pricey at 12p ea.) which have 6 pins, 3 on either side, giving the switch stability in breadboard use.. Panel mount: Fancy colored latching push-button switches, 10 pc. for £7.86 (79p ea.)
7. Slide Switches:
  Excellent for building custom UIs for HW configuration, combined with shift registers. 1PxT switches can be used instead of more expensive rotary switches, or microcontroller solutions.
  
  WARNING! Panel Mount switches are not likely to have pins that fit standard breadboard pitch of 2.54mm. Even PCB mounted switches may not have standard pitch (e.g. 2.0mm or 1.5mm). Be sure to check with the seller/vendor!
  - (tried) 1P2T slide switch: Breadboardable: Lowest: 50pc. for £1.04 (2p ea.). Currently: £4.68 for 100pc (4.7p ea)
    Panel Mount: 20 pc. for 13p (<1p ea!)
  - (tried) 2P2T slide switch on/on 10pc for £3.14 (31p ea) or for £7 (70p ea) next day, or for £6.50 (65p ea) right angle switch next day
  - (tried) 1P3T (4 pins): PCB Mount: Panel Mount: 20pc for £6.50 (33p ea), or slide switch 5pc for £4.50 (90p ea) next day or right angle 10pc for £4.20 (42p ea) or 20pcs for £5.34 (25p ea)
  - (tried)2P3T (8 pins): PCB Mount: 20pc for £7.70 (39p ea)
  - 1P4T rotary switch £6.12 for 2pc (£3.06 ea),
  - (tried) 1P4T slide switch: 10pc for £10 (£1 ea), 3 days (ebay)
  - (tried) 2P4T slide switch: PCB ready (2.54mm standard pin pitch), 5pc for £4.35 (87p ea) ebay, or 5pc for £6.50 (£1.30 ea) 2PxT switches can implement any $2^n$ choice. WARNING 1 When using in breadboard, this will be a 1P4T as the pins are not separated far enough apart to straddle the IC chip divide to keep the two poles separate. WARNING 2 The case is metal so be frugal with soldered connections to avoid shorting to the case (test that this has not happened before live test).
  - (tried) 3P4T £1.30 ea
  - 1P5T £8 rotary
  - (tried) 2P5T rotary switch 2.26ea
  - 8P5T rotary 6mm, £5.24
  - 8P5T rotary 6mm, £5.24
  - 1P6T £3 with knob, or £3.12 (was £1.30)
  - 1P7T £6.37 or £7.50
  - 2P8T, £9
  - 1P10T £9.50 next day
  - 1P12T £7 next day
  - 1P16T – cool rotary hex entry switch $3 ea
8. DIP switches:
  Kit of 35 pcs for £5.27 (7 varieties, 5 each, 15p ea.)) or Kit of 44 pcs for £7 (6 varieties, 10ea. of 2-,4-,6-,8- position and 2ea. of 10-,12- position, 16p ea.)
  or Individually:
  1-bit (DIP-2 pins), 10pc. for £1.11 (11p ea.) Note: you’re better off with breadboard-able SPST slide switch at 2p ea.,
  4-bit (DIP-8), 5pc. for 89p (18p ea.),
  5-bits (DIP-10 pins), 8pc. for £1.35 (17p ea.),
  8-bit (DIP-16 pins), 10pc. for 98p (10p ea.) or 10pc for £3.20 (32p ea.) or 10pc for £2.20 (22p)
  10-bit (DIP-20 pins), 10pc. for £1.87 (19p ea.)
Relays
Relays can be latching (with memory) or non-latching (without memory), or momentary. Dual-pole Relays allow connecting independent circuits, one to each pole. The number of poles indicates the number of basic states. While a dual-throw switch may also have a center off position for relays this requires adding another relay to manage power. Connecting DPDT relay
1. DPDT 8 pins – wiring diagram
  12VDC 10 pcs for £3.51 (35p ea), mini size, 10 pc HK19F for £10.07 (£1.07 ea), 10 pc HK19F for £9.90, three days
  
  9VDC Omron G5V-2-H1-DC9 DPDT 1A 9V NON-LATCHING (DigiKey UK), £4.96 (for 2 pc) – All DigiKey (16 relevant) – these aren’t cheap UK sources: RS-Online, Omron G5V-2 9DC £2.81 ea. in pack of 5 and Farnell, Schrack RT424009, £2.88 ea. in qty x1 or Jameco Electronics, Kemet UA2-12NU
  
  5VDC Omron G5V 5 pc for £4 (80p ea) ebay
2. SPST
  5VDC 10pc for £4.40 (44p ea), or £6 for 5x KY-019 relays (£1.20 ea.) w/ Prime Delivery or £5 for 3x KY-019 relays (£1.66 ea.) or £5.50 for single board with 4 channels
Buzzers (Active) and Speakers (Passive)
1. Active Buzzer 5VDC, 85dB, 12mm or 6V-12, 10mm, 85dB@5V
2. Siren/Alarm (Active) Buzzer (DC): BJ-1K 100dB, 40mA draw at 5V (200mW), externally mountable alarm speaker, £3. BJ-1K is a definite ear-splitter even at 5V.
3. Loud PASSIVE Buzzer, 1300+/-500Hz (1 full octave), 85dB, rated to 12VDC., 2pc for £5 (£2.50ea). Note requires oscillation circuitry.
4. Mini Speaker, 8-ohm load (measure resistance/impedance directly and round up to 4,8,16 ohms) :
  ASSEMBLY TIP: when soldering wires to a speaker, or if it comes with wires attached, use hot glue gun to put a drop around the solder points. This provides strain relief against the speaker wires. If those come off or pull off the solder pad, the speaker is unrecoverable.
5. 0.25W 2″ speaker sounds much better than 1W PC mini speaker. | Advice on sounding better (avoiding clipping and distortion).
  1. 0.25W speaker: Lowest price: 2″ (50mm) diameter ultra-slim, £1.01 ea. (Spiratronics). Current price: 1.6″ (40mm), £2.90 (Spiratronics) comes with attachment points for cables or clips
  2. 0.5W speaker 28mm, 4 pc. for £1.08 (27p ea.) or 28mm, 4 pc. for £1.30 (33p ea.) attachment points are solder pads – requires a soldering iron
  3. 1W speaker, Lowest price: 29p ea (10pc for £2.91) | Current price: 28mm, 10 pc. for £7.50 (75p ea.), 3 weeks
  4. 1W PC Speakers: 10mm diameter: 5pc for £2.54 (51p ea.) or 5pc for £2.66 (53p ea.), each with “PC” speakers, 1W,
    w/ pigtail wires 26 AWG (need to use grabber probes and 22 AWG wire to use with breadboard, or solder onto 22 AWG wire – note the wires have limited strength; if they break off the speaker is toasted — see ASSEMBLY TIP above)
  5. *good* 2W speaker, round:2pc for £5 (£2.50 ea) 3 weeks, 22mm/1.1″, 2pc for £6 (£3 ea) next day, or 2pc for £8.50 (£4.25 ea) next day, or 36mm 10pc for £13 (£1.30 ea), 6 weeks
  6. *best* 5W speaker (no need for amplification IC): Oval broadband speaker 70mmx30mm 4pc for £10 (£2.50 ea) next day or 4pc for £8.50 (£2.12 ea) or 4pc for £5.62 (£1.40 ea) incl. S&H (lowest price 90p ea)
  7. 10W speaker: 2 for £7.01 (£3.50 ea.) 30-day shipping
  8. Bluetooth Wireless speakers (consumer product not electronics component): Ewa, £10, IP67 (Waterproof) or Lenrue £13, IPX5 (Shower/Outdoor)
    Note, sub-1W PC speaker (10mm diam.) does not need amplification to be heard when testing, provided use a 100uF coupling capacitor and voltage to speaker is large enough. In applications an amplifier chip will be useful (LM386 IC is easy to use, supports 9V input, and is inexpensive). A 5W speaker does not need anything to be heard quite well.
    
    Be careful of applying too much heat — if the solder pad comes off, the above inexpensive speakers are likely toast. Scraping back the black seal with a knife does not reveal a wire to connect to.
    
    I use hot glue to provide a protective seal around the solder pads/wires once they are soldered on, to prevent mechanical pressure lifting the pads up.
1. KENABLE audio store @ Amazon – good prices, deliver in a few days, all things audio
2. Mono TS (tip sleeve) audio cable, M-M, right-angle/regular: 0.5m £1.94, 1m £2.05, 2m £1.78, reg/reg 0.5m, 1.0m, 1.2m, 2.0m, 3.0m, 5.0m, £1.91-£3.03
3. Audio Adapters: 6.5mm mono coupler F-F (socket-socket), £1.80, | F-M (socket-to-plug) **6.5mm mono socket to 3.5mm mono plug, £1.94 or 5pc for £7.30 (£1.46 ea) next day works great for plugging into electronics 3.5mm female pcb mounted socket to allow the device to be connected to an amp using standard amp MONO TR cables (6.5mm M-M) | 3.5mm stereo socket to 6.5mm mono plug, £1.76, WARNING: this shorts the two stereo channels and sends them to TIP, 3.5mm mono socket to 6.5mm stereo plug, 3.5mm stereo socket to 6.5mm stereo plug, 3.5mm separate mono sockets to 3.5mm stereo plug (c.£1.80 ea, £2.30 for latter – Kenable store)
4. Behringer MX400 4-channel line level mono mixer – £18 next day – perfect for combining multiple electronic instruments and sending into a single amp! 🙂
5. Breakout: 3.5mm mono socket to 2-pin terminal block, 5pc. for £9 (1.80ea)
6. PCB mount: 3.5mm stereo socket to 4-pin pcb mount connector (non-breadboardable), 15pc for £4 (25p ea)
Diodes The stripe indicates the negative terminal. Forward voltage drop of 0.7V.
1. Rectifier Diodes – 1N4001 50V 1A 25 pc for 50p (2p ea.) or 50 pc to £2 (4p ea.), 1 week (note, under magnifying glass can see 1N4001 written around barrel)
2. Signal (Switching) Diode – 1N4148 300mA 50 pc for £2.00 (4p ea.) (reddish glass with black stripe)
3. Zener Diodes – 0.5W rated Lowest price: 0.8p ea (300pc for £2.40), 1W rated: £3.95 for 250pc (1.6p ea) 3V-33V 25 values 10pc ea
  Used to ensure a minimum voltage supply / detect a MINIMUM voltage violation (e.g. low battery, and shutdown). Can use to build your own buck (stepdown) voltage converter and regulator circuit | Calculate the current through a Zener like this: V_source – V_Z / R = I_eff | Maths for working with Zener Diodes | why it doesn’t work on real (non-constant) loads (I tried it with the analog piano) – the battery sagged less than the diode! | Similar explanation – zener diodes only regulate at low current with fixed load, i.e. they are useful to provide reference voltages | Remember you need an adequately sized resistor to dissipate the delta between V_source and V_z or if the load current varies between max and min (e.g. volume control on audio), or the zener diode will run hot.
Display Elements / Lights I recommend getting 4x 7-segment displays (for a basic 2 digit calculator, 1 serial (16-pin) 1602-LCD display to understand such displays, but then use OLED I2C displays for all of your standard display needs)
LCD (liquid crystal display), TFT (thin film transistor) LCD, OLED (organic LED), MicroLED, and QLED (quantum LED) display technologies. Gist: LEDs are lower power light-emitting diodes. OLEDs, MicroLEDs, and QLEDs use these as individual pixels which means no backlight required. By contrast, LCDs require an always-on light source (backlight) which is blocked or allowed to shine through the liquid crystal interface using electrical charge. By creating granular spatial control of the LCD surface, the technique can get pixel-level control instead of the usual calculator-like segments.
1. 7-segment display, Red LED 0.5″ 10-pin, 10 pcs £1.15 or Kingsbrite SC56-11EWA 0.56″ height, low current, red common cathode (Digi Key), £3.20 (3 pcs)
2. LCD display 1602-module (16 characters per row, 2 rows), 5VDC, HD44780 LCD controller chip, 80x36x10mm:
  - 16-pin (serial) 1602-model requiring 7 I/O ports to control: £2.02 (without pins) or £6.68 for 5pc (£1.34 ea) without pins, or £4.00 Prime Delivery
  - 4-pin (I2C) 1602-model, I2C interface requires only 2 I/O (data) pins to control. Backlight & contrast can be manually controlled with potentiometer and/or jumper pins: £1.96 or £9.78 for 3pc (£3.26ea) with Prime Delivery
  - 4-pin (I2C) 2004-module (20 characters per row, 4 rows): £3.50
  Reference: Connecting the serial 1602 to a breadboard
3. OLED Display: Organic LED is a high luminosity self light-emitting technology that does not require backlight and so uses lower power than LCD. High pixel resolution allows displaying graphics through individual pixel manipulation, and text. Device driver readily available (see below) Note, all OLED displays below use the SSD1306 driver IC chip. These are about half price vs. those that use SH1106 driver chip (advantage of latter is Tiny Graphics Library that does away with buffer writes, so can fit on ATtiny85 MCU). | Tiny Tetris demo with real-time (unbuffered) drawing and detailed post here | Default address is 0x3C. Can change to 0x3D using SMT resistor to back of board, or using I2C multiplexer, or custom library with one SDA line per display
  1. comprehensive catalog on Ebay – all sizes and comms types
  2. 128×32 pixels (4 rows of text) 0.91″ I2C interface (4 pins): Low: £2.10ea £8 for 2pc (£4ea, without pins) with Prime Delivery
  3. 128×64 pixels (8 rows of text), 0.96″, blue, white, or yellow-blue: lowest price: £2.13. Currently: 6pc white or blue for £18 (£3.00 ea) same day
  4. 128×128 pixels 1.5″ (16 rows of text: cheapest price: £5.86 (expired). Active: £12.82 next day
  5. 128×64 2.4″: £10.50 (SPI)
  6. 128×64 2.7″: $50 (SPI)
  OLED Display is driven by SSD1306 display chip. Driver for use with Arduino is Adafruit’s ssd1306_i2c.ino. Tutorial for connection and use.
  
  These 128×64 pixel I2C OLED displays are crisp, sharp, and bright. Easy to display text or turn on individual pixels (graphics) by using device driver software (Adafruit_SSD1306.h/.cpp and Adafruit_GFX.h/.cpp) for the integrated SSD1306 driver chip. Because they are I2C controlled, you need only use 2 pins on your microcontroller (not including 5VDC power/ground) instead of 4 pins for SPI control or more pins for standard LCD.
  For advanced users, it’s also possible to control the OLED display directly through I2C by sending byte commands and graphical data to the SSD1306 chip without requiring a software buffer reducing memory consumption. I’ve written an Arduino Forth to make this easy. One neat feature built-into the SSD1306 is software configurable scanning direction control which means the display can be mounted in 4 different ways and the content can be screen flipped on the fly. Watch-out: careful you check whether you are buying single color or dual color display (e.g. Yellow/Blue). The colors can’t be changed. (For that you need a TFT display.)
  Bottom line: this is an elegant, aesthetic, and highly versatile device, easy to use for beginners and advanced users alike.
4. TFT Full 18-bit color Display with SPI (4-wire) interface, SD Card Reader, and ST7735 image controller:
  1. 1.8″, 128×160 pixels, SPI: £4.20 next day or 5pc for £20 (£4 ea)
  2. 2.4″, 324×240 pixels, SPI: £9.80 next day or 3pc for £23 (£7.60 ea) or 5pc for £34 (6.80 ea)
  3. 3.5″, 480×320 pixels touchscreen/touchpen, SPI: £18
5. Flashing Lights: £16 for 7.5W, 12V, (1.6A), (short cable) or £20 for 12V, 25W, (2A), 30 LEDs, magnetic mount, configurable flashes or £9.28 for 10V rotating beacon or £12 for 12V rotating beacon
6. LED Bargraph Display (aka fuel gauge indicator). 10-segment Green only, Yellow only, or Red only, £1.07 ea. (Spiratronics) or 10-segment Greenx7/Redx3 – £3.37 for 2pc. (£1.68 ea.); 10-segment Red, £1.40 for 1pc. or £1.46 for 1pc.; 10-segment Red/Yellow/Green/Blue, £1.50 for 1pc.;
7. LED 10-segment IC Driver Chip LM-3914 £2.66 (Spiratronics) or LM-3914 £5.20 for 1pc. (linear display) and Instructions from Sparkfun
  Three common 10-segment IC driver chips are LM-3914(linear)/3915(3dB)/3916(-20db to +3db). The latter two are usually used in displaying audio signal strength. Video example and skywire demo
8. LED Tower Light RYG with Buzzer on flexi-mount, $27.50, Adafruit

2026 : Continue on to Part 2!.

manual-range-select (not auto-ranging). Manual ranging instills the useful discipline of selecting the appropriate measurement range and there is no software delay in the measurement ↩

Mathematical Science & Technologies

Electronics

Exploring Electronics on a Budget

What to Buy, When to Buy It

The Equipment List

0. Recommended References

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Soldering: The Fine Art of Fine Soldering

RECOMMENDED ADDITIONAL SOLDERING COMPONENTS FOR SERIOUS DIY

B. Components & Supplies

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Maths Education

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Mathematical Science & Technologies

Electronics

Exploring Electronics on a Budget

What to Buy, When to Buy It

The Equipment List

0. Recommended References

A. Equipment

Soldering: The Fine Art of Fine Soldering

RECOMMENDED ADDITIONAL SOLDERING COMPONENTS FOR SERIOUS DIY

B. Components & Supplies

Dear Readers:

Reading List…

Mathematics History & Philosophy

Topics in Mathematics: Pure & Applied Mathematics

Technology: Electronics & Embedded Computing

Technology: Sensors & Intelligent Systems

Maths Education

Browse…

Explore…

Timeline