Chapter 23 - 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


Show everything in a circuit sim, fix heading levels (this is a mess)

Possibly break up this chapter? Transistors, the opamp, etc alone may each justify their own chapters

That said, I don’t want to get to in the mud of transistor physics. I really want to focus on how/when/why to use what, not how they work as the physics is both pretty hard to grasp and not super useful. Still would like to mention that switching is what uses power and like process size things, but maybe not the chemistry or electron tunneling effects, at least not in great detail

Chapter 23.1 - Semiconductors #

TODO, looks very good briefly scrolling though 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 super good)

Alright, so in very basic terms, it’s a part that only lets current flow in one direction (idealy). 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 recomend 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

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


tIGBT, Mosfets? #

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

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

Chapter 23.2 - Op-Amps & Filters #

Op-Amps #

Handbook of Operation Amplifier Applications (TI)

Optical Electronics #


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 23.3 - Safe Circuits #

Protecting Inputs in Digital Electronics (Digi-Key)

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

Chapter 23.4 - Rare and Dangerous Componets #

  • Dangerous
    • Tesla coils
    • High voltage/current/hot/whatever
    • Don’t pretend to be an electrician
    • Don’t use ATX psus for dumb things
  • Rare/Expensive
    • Tubes, NOS parts, etc. - TODO: CRTs and Aquadag

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 Patreon or dropping me some spare change on Venmo @vegadeftwing - every little bit helps ❤️