[sdiy] Music Easel timbre generator, resistors in parallel

[Harry Bissell Jr]

Some people put a carbon comp resistor and a metal
film resistor together to affect the overall tempco
of the part... usually in series.

I'd think more like "circuit tweak" than anything
else...

H^) harry

--- Aaron Lanterman <lanterma at ece.gatech.edu> wrote:

> 
> Hmmmm....
> 
>
http://rubidium.dyndns.org/~magnus/synths/companies/buchla/Buchla_2080_9_200.jpg
> 
> It doesn't use the CA3160s for rail-to-rail
> operation like in the 259 
> timbre generator - it uses the RC4136, which look to
> me like a quad 
> version (with weird pinout) of the 4558. The
> schematics of the two op amps 
> look identical.
> 
> Anyway... in addition, Buchla does this weird think
> with resistors in 
> paralell. Like, there's a 49.9K 1% in parallel with
> a 5% (I guess) 390K... 
> and a 1.5 Meg (5% I guess) in parallel with a 75K
> 1%. What's the logic 
> there? Why not just put down a 72K 1% or whatever?
> 
> - Aaron, trying to understand the depths of
> Buchlalogic
> 
>
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