[sdiy] ASM-1 VCO troubles another time

[Chris Crosskey]

Thisd is prolly my fault...I just checked my VCO's...I used BF-somethings in
there, not the 2N3819....that went into a S+H circiut I built.....sorry..

chris

> -----Original Message-----
> From: Fortner Florian [mailto:florian.fortner at fh-joanneum.at]
> Sent: 23 April 2002 08:52
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] ASM-1 VCO troubles another time
> 
> 
> Hi List,
> 
> You boys were right, it WAS the J-FET! The 2N3819 is simply 
> to slow to reset
> the Integrator cap, I soldered in a J111 (30 Ohm , 5-7ns 
> risetime) and the
> VCO works just fine!
> But there is another funny thing: I have two VCO's on the 
> PCB, feeding both
> with the same CV of, say, 50mV (at the base of the 
> exponential pair), I get
> a nice 1.4kHz saw from one of the VCO's, but the other one 
> "swings" with
> 15kHz. How's that possible?? I have everywhere the same part 
> values, the
> trimmers are in the same positions, so I can't find the bug.
> Is it normal that the Squarewave moves up and down when I turn the
> Pulsewidth knob? Looks strange on the oscilloscope, but yet I 
> didn't listen
> to it.
> 
> regards,
> 
> flo
> 

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