[sdiy] SSM2164 VCA

Neil Johnson neil.johnson97 at ntlworld.com
Sat Oct 30 11:34:33 CEST 2010


> All the designs I've seen based on the Mike Irwin design change  
> Vref to whatever they want the CV range to be. Is there a reason  
> why you couldn't just use -15V and scale the resistor connected to  
> Vref to suit? Wouldn't the 2164 just be seeing a current input, and  
> not care what voltage is on the other end of the resistor?

A couple of quick observations:

1/ What happens if my "+15V" is not actually +15V, but perhaps +14V?   
Or is someone wants to run your module from +12V?

2/ Any noise on the rails (and they are generally noisy, shared  
across all modules) will couple very easily into your signal path.   
Unless you consider this desirable I'd say save up your pocket money  
and splash out on, at the very least, a 5v1 zener or even better a  
proper voltage reference diode.


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