[sdiy] 1k tempcos

[Mattias Rickardsson]

Thanks guys for many good points of view, also regarding the somewhat
different needs in commercial synths. I'll stick to my +3300ppm
tempcos for now. :-)

/mr


2008/7/10 Ian Fritz <ijfritz at comcast.net>:
> At 02:57 AM 7/10/2008, Louis van Dompselaar wrote:
>>
>> What do these VCOs actually require?  Some if not most
>> DIY-ones are actually designed to take +3300ppm or +3500ppm
>> tempcos.  Actually, I don't think I have ever seen one that requires
>> +3000ppm (but someone will prove me wrong).
>
> The correct value is 1/T = 3360 ppm/K.  Most tempcos have a tolerance in the
> tempco of at least +/- 10%, so a 3300ppm unit might be in a range of 2970ppm
> to 3630.  For critical work it's best to start with a high value and pad it
> down with a series metal film resistor.  Or use my dial-a-tempco scheme to
> bring it in exactly.  :-)
>
> http://home.comcast.net/~ijfritz/sy_cir9.htm
>
>  Ian
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