[sdiy] THAT 2180 as current switch

[Aaron Lanterman]

On Sun, 23 Apr 2006, Chad Cosby wrote:

> I'm trying to make the make Buchla's triangle-core oscillator using a 
> amp w/ exponential gain control (THAT 2180 or SSM2164) as the 
> exponential converter and the current switch.  Does any one know if I 
> can get one of these guys to behave like Buchla's voltage starved OTA?

Yay! I think this is the first post by an Aaron student on the board.

Chad: I wouldn't call it "voltage starved" - you'd want to call it 
"overdriven," so you're into deep into the "tanh" function of the OTA - 
but I'm not sure what the equivalent behavior of a SSM2164 or THAT2180 is.

Group: Chad's the only one trying anything like a traditional VCO design 
(sadly, no other students took on such a project. A few are trying to make 
some oscillators not traditionally used for VCOs into VCOs.)

I do know someone used an SSM2164 as an expo converter for a sawtooth 
core, but I hadn't seen anyone do it with a triangle.

Chad has a SSM2164 and a THAT2180 that I gave him to play with, as well as 
a fast LM319 comparitor.

Feel free to give Chad advice. In particular, if there a reason you see 
ahead of time that this _won't_ work, that would be good to know!

Thanks!

- Aaron

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