[sdiy] Help with Timing Capacitor types.

[Mike Beauchamp]

Thanks Paul, I appreciate the advice.
The 2206 chip is just damn fun in my opinion and I've been messing
with it for 3 years now making various little fun things. I'm aware of
it's shortcomings obviously, but there's something very fun about it
for me, and I like "hacking" weird sounds out of it.

So, all "badness" aside, I will plan on using ECQ-P caps in there. :)
Thanks for setting me straight on the mylar thing. Speaking about
modems, did you ever tell your "funny modem capacitor story" as
mentioned in the old concertmate post?

Mike


On 3/4/07, Paul Schreiber <synth1 at airmail.net> wrote:
> a) Errr....a 2206 "badness" will 'swamp' pretty much all of any cap 'badness'.
>
> b) The tempco of the cap is not the 'reason' it is picked in VCOs. It's the
> dielectric absorbtion factor. Sure, a 100ppm tempco helps and in the MOTM-300
> VCO, there is a specific tempco loop for the cap. A mylar cap is the *worse
> possible* choice. You are better of with a polyproplyene cap (Digikey sell the
> Panasonic ECQ series) rather than Mylar any day. Remember, cap technology has
> also advanced in the last 25 years. There is *no reason whatsoever* in using a
> Mylar cap (even if they are free).
>
> Use Digikey part # P3921 at a staggering 60 cents :)
>
> Paul S.
> BTW: for the Tandy 300 baud modem filters I designed in 1980, we used about 1.7
> *million* ECQ-P caps 1% at 4700pf. Worked great!
>
>


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Mike Beauchamp
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