[sdiy] Expo converter tempco placement

[David G Dixon]

The answer to your question undoubtedly lies in mathematical modeling.  I
haven't done it for tempcos as I don't use them -- I use the famous 2164
expo and tempco scheme in my VCOs (and sometimes in VCFs), and I've modeled
the crap outta that.

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Justin Owen
> Sent: Wednesday, July 09, 2014 8:40 AM
> To: SDIY List
> Subject: [sdiy] Expo converter tempco placement
> 
> Hello,
> 
> Can anyone give any insight into the differences between the 
> two main locations for tempco placement in expo converter circuits? 
> 
> Seems like the schems I have are divided fairly evenly 
> between those who use a tempco (generally 2K) in the feedback 
> loop of the CV scaling op amp that feeds into the base of the 
> expo pair and those that use a tempco (generally 1K) as part 
> of a voltage divider at the output of the CV scaling op amp.
> 
> Secondly, if you were using a tempco int he feedback loop of 
> the CV scaling op amp - would there be any problems using 
> that tempco in parallel or series with another standard R to 
> achieve a certain R value?
> 
> Thoughts?
> 
> Thanks!
> 
> - Justin
> 
> 
>  
> 
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