Things you can do with diodes

(lcamtuf.substack.com)

325 points zdw | 1 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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RossBencina ◴[04 Nov 25 02:08 UTC] No.45806767[source]▶

>>45806185 #

4. Voltage controlled filter, (diode ladder VCF), as used in the Roland TB303

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1. ErroneousBosh ◴[04 Nov 25 12:43 UTC] No.45810301{3}[source]▶

>>45806767 #

Diode ladder, but also in various Sallen-Key designs like the Steiner-Parker Synthacon which we all now know from the Arturia Minibrute (Yves Usson probably made more of these filters than Nyle Steiner ever did!) and as I've mentioned elsewhere the Korg MS50. I think the Yamaha GX1 filters used a diode bridge too, probably using discrete transistors similar to the Korg 700S filter.

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