Chapter 24 - Circuits & Semiconductors #

When I was a kid I thought about circuits as being alive, like Cells at Work!, only little electrons going around busily keeping the heart of my toy working instead of anthropomorphic red blood cells working in the human body.

Now, as an adult - and a computer and electrical engineer at that - I still find this thought endearing. Though I’ve now come to see the physics and art of electronics to be even more beautiful when their true nature is really understood.

There’s a joke you’ll hear about those that work with these low level physics or that arrange logic gates to make full CPUs- that our job and passions boil down to teaching rocks to think.

So, let’s lean how to teach some rocks.

©Vega, made with Noisedeck, inspired by pictures of silicon wafers, like this one.

Chapter 24.1 - Semiconductors #

TODO, looks very good briefly scrolling through it:

Digilent’s ‘Real Analog’ course looks okay too, and I might write this guide assuming their analog parts kit:

Semiconductors? #

Will gallium nitride electronics change the world? (YouTube, Engadget)

[TODO] pic of silicon bulb

P/N junctions, etc.

Diodes, the one way road #

A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other.

Diode page on Wikipedia (which is actually superb)

Alright, so in very basic terms, it’s a part that only lets current flow in one direction (ideally). A one-way road for current. If you put a sine wave in, you’ll get a sine-wave chopped in half out. Now, this assumes everything is ideal, as you’ll really get more like the top 40% of the wave out, but we’ll get to those details in a bit. For now, I recommend watching these videos:

zeener, normal, bipolar

  • varistors , sparkgaps
  • Leds - getting current both ways, LED safety

Zener Diode (YouTube - EEVblog)

Varicaps (Wikipedia)

Tunnel Diodes (Wikipedia)


DIY Diode (Simplifier) Part 2 Part 3 Part 4: Power Diode

Diode Logic #

The Diode Clock

Transistors #


Transistor Families (JonDent - Blogspot)

Bipolar Transistor @

tubes and how they work

Introducing Triodes (Aaron Lanterman - GT, YouTube)

DIY Triode (Simplifier) Part 2 Part 3 Part 4 Part 5: Power Triode Part 6: Power Triode 2 Part 7: Portable Triode, Tetrode


Mosfets? #


IJBTs? #

Tubes #

That Elusive Valve Amp Sound, For Not a Lot! (There has to be a Catch) (

Integrated Circuits #

[TODO] Uncovering the Silicon: Demystifying How Chips are Built and How They Work (YouTube)

Reverse-engineering the TL431 backup of the above embedded tweet backup of the above embedded Tweet + copy of the image

555, OpAmp, 74-Series Logic #

555 Timer IC (YouTube)

555 as an amplifier (don’t actually do this!)

Tiny Transistors’ Clever TT555 Is a Pin-Compatible 555 Timer Built from Discrete Components (

potato semi

[TODO] note on price of chips that solve bigger problems - integrated filters, PLLs, VCAs, basically everything on this list

Chapter 24.2 - Op-Amps & Filters #

Op-Amps #

Handbook of Operation Amplifier Applications (TI)

These things aren’t actually ideal! #

  • Not all OpAmps are rail-to-rail, meaning if you give them -12 and +12 V rails, you may only be able to hit -10 and +10 or so.
  • OpAmps really need clean power. If you don’t put a small cap to filter the power right at the OpAmps VCC and Gnd pins, except noise.
  • There will almost certainly be at least a little bit of DC shift in the output
  • You do not actually have infinite gain
  • You do not have infinite bandwidth
  • They do not actually have infinite input resistance, it’s just really high.
  • … See Real op amps, non-ideal aspects (Iowa State University : EE 230, PDF)

Optical Electronics #


Opto Isolators, Vacttrols, Photoresistors

Crystal Oscillators #


Piezoelectricity - Why hitting crystals makes electricity (YouTube)



Driving a PAL tv over RF thanks to PWM harmonics (Hackaday)




Active Filters #

Chebyshev Filters (YouTube - All About Electronics)

Butterworth Filters (YouTube - All About Electronics)


Waveguides #

Waveguides Explained (YouTube)

Audio Devices #


speakers, piezos, amps, mics and pickup patters


add motors, analog meters, various connection standards, radio, flex/pressure sense, grounding (chassis, digital, analog, ground planes, etc.), solar/photo reactive,

Relating AC and Music #


Relate back to things like ADSR, Distortion, Reverb / Echo, Decibels (audio), etc. Use VCV RACK

Chapter 24.3 - Displays #

There are many Reasons to Question Seven Segment Displays (Harold Thimbleby), especially today, as using literally anything else has gotten significantly easier.

[TODO] Eink, OLED, TFT, etc.

Russian nixie, VFD and numitron overview (Just another electronics blog)

Also, you may want to be able to update your display quickly, so keep in mind if your controller/device has either a native video output, or at least DMA that you can abuse (Just another electronics blog).

Chapter 24.4 - Safe Circuits #

10 Ways to Destroy an Arduino (Rugged Circuits)

Protecting Inputs in Digital Electronics (Digi-Key)

Why 10,000 Volts at altitude is a Bad Idea (YouTube, Strange Parts)

TODO: Efuses

Chapter 24.5 - Parts & Tools you’ll want to be aware exist #

Tools #

  • Wirewrapping

Parts #

Chapter 24.6 - Rare and Dangerous Components #

Continued Reading: #


At this point I highly recommend ‘Practical Electronics for Inventors’ ISBN 978-1259587542, namely chapters 2-12, and 15-16. It’s a very large, detailed book that does its best to keep things, well, practical.

Hardware isn’t generally copyrightable 2020 Circuit Sculpture Challenge

RGB LED, Inductively Powered, Frequency Controlled (YouTube, Wolf Tronix)

How to protect circuits from reversed voltage polarity! (YouTube, AfroTechMods)

Circuit Sculpture Workshop (Hackaday, Kristina Panos)

Current Loop (Wikipedia)

If you would like to support my development of OpGuides, please consider supporting me on GitHub Sponsors or dropping me some spare change on Venmo @vegadeftwing - every little bit helps ❤️