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Things you can do with diodes

(lcamtuf.substack.com)
325 points zdw | 3 comments | 03 Nov 25 23:49 UTC | HN request time: 0s | source
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dietrichepp ◴[04 Nov 25 00:27 UTC] No.45806185[source]▶
Conspicuously absent are some of the analog circuit applications. Here are three of my favorites:

1. Frequency mixer, used for heterodyning, important in radio, so I hear. https://en.wikipedia.org/wiki/Frequency_mixer

2. Log converter, where the output voltage is proportional to the logarithm of the input voltage. https://electronics.stackexchange.com/questions/374440/log-c...

3. Diode ring, which provides variable gain, used in analog compressors like the Neve 33609 (I have a clone of the 33609, and I’m very fond of it)

Think about this: if you have a nonlinear device like a diode, then the dynamic resistance changes depending on the operating point. If you modulate the operating point, you’re modulating the dynamic resistance.

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1. exDM69 ◴[04 Nov 25 09:20 UTC] No.45808965[source]▶
Two more from the world of analog music/guitar electronics:

1) Ring modulator: https://en.wikipedia.org/wiki/Ring_modulation

A device used to multiply two analog signals in time domain. Best known for the sound of the Daleks in the original 1960s Doctor Who series. Has some applications outside of music and sound effects. If you can find those old fashioned audio transformers, this effect does not require a power source.

2) Diode clipper: https://en.wikipedia.org/wiki/Clipper_(electronics)

Two diodes in parallel with opposite polarities. Clips the incoming AC signal to a +/- diode threshold voltage. Put a high voltage gain amplifier stage in front of it and you get the classic electric guitar distortion tone you know and love. Allegedly works best with germanium-unobtainium diodes. In their absence, using two different kinds of diodes can also have pleasant tonal qualities.

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2. ErroneousBosh ◴[04 Nov 25 12:39 UTC] No.45810249[source]▶
> 2) Diode clipper: https://en.wikipedia.org/wiki/Clipper_(electronics)

I don't even know how many Boss DS-1 clones I've made, but the first one was probably when I was in high school about 35 years ago.

3. actsasbuffoon ◴[04 Nov 25 15:35 UTC] No.45812153[source]▶
So many distortion pedals use an op amp to run a signal into antiparallel diodes to create distortion. I’ve spent a few weeks trying to emulate it, and it’s a lot of fun.

Different flavors of diode make significant changes to the way it sounds. Even things like LEDs can be used (they are Light Emitting Diodes, after all).

Andy Simper of Cytomic is some kind of mad genius at this stuff. He’s created a painstakingly accurate emulation of the Ibanez Tube Screamer that allows you to change the values of basically every component in the circuit diagram. It’s jaw dropping: https://cytomic.com/product/scream/

He’s also shared a ton of incredible information about how he emulates circuits. The math can get really intense. If anyone is looking for a fun project, I strongly suggest experimenting with circuit modeling. It’s a great workout for the brain.