[sdiy] low voltage filters

[Roman Sowa]

You can make discrete VCA, or should I say differential amplifier with 
controlled gain, working at 3V and probably less too.
Differential pair, current mirror at the top, transistor at pair's 
emiters to control current. It will be dirty and bit tricky to control, 
but you wanted character anyway.

Roman

W dniu 2017-04-19 o 21:38, Chris McDowell pisze:
> Howdy list!
>
> Wondering if anyone is aware of, or has any tips towards, some low voltage VCF designs. I've seen reports of people using LM13700s with a single 5V supply for VCAs, and their one-off forum posts made them seem happy, heh. I realize this would have very little headroom. I've also checked out Hoshuyama's site, which has a few battery-powered designs. Some things I've considered:
>
> - Perhaps LM13700 just works at 5V ¯\_(ツ)_/¯ (avoiding breadboard as long as possible…)
> - Discrete OTA with BJTs
> - MS-20 Style, like the monotron
> - Vactrol, H11F1, or similar
>
> The point of this is that I have DCOs and ADSRs working wonderfully in a 3.3V environment. Some dirt is okay, I say. Super ideally, I want to implement an SVF with a single 3.3V supply, suggestions toward reality / sacrifices are welcome. I imagine this would work fine with vactrols, but I don't want to design anything with parts I can't buy from mouser, hehe.
>
> Cheers,
> Chris
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