[sdiy] VCO that goes SHARP in highest octaves??

Ian Fritz ijfritz at comcast.net
Fri Jun 17 20:04:10 CEST 2022


Something else you might try: reduce the values of the integrating cap and the reference current by a factor of two or so. This could possibly reveal any self-heating in the expo transistors.

Ian

> On Jun 17, 2022, at 11:41 AM, Neil Harper via Synth-diy <synth-diy at synth-diy.org> wrote:
> 
> 
> 
>> On 6/16/22 02:48, Maarten Halmans wrote:
>> Hello Neil,
>> 
>> Are you sure the problem is in the higher octaves, didn't you compensate
>> for a problem on the low end resulting in the oscillator going sharp in
>> the higher octaves? I had this twice with a Jupiter-8 oscillator, once
>> it was caused by flux and the other time by a leaky FET.
>> 
>> Best,
>> 
>> Maarten
> 
> 
> Hi maarten, I am doing nothing to compensate for the low end. the
> oscillator design just has a scale adjust and a high-frequency trim
> adjustment.
> 
> interesting about the flux though.. my thru-hole version was
> water-soluble flux that I cleaned off manually. the SMT board was done
> by the assembly place using a no-clean flux.
> 
> --
> /// Neil Harper
> /// Every Wave is New Until it Breaks
> 
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