[sdiy] Old unique VCO - Tune drifting problem - adapting a servo conversion‏

Idris El Kasri idris1er at hotmail.com
Wed Jun 13 17:41:06 CEST 2012


  Sorry, if I disconnect the collector of the conversion transistor on the original circuit (http://img826.imageshack.us/img826/646/vco2shematic.jpg) I got for instance -9,7V on the collector and -9,2V on the base...
  Is it possible to get these values with a matched pair for the conversion?
I found this doc for the exponential conversion with a matched pair but unfortunately I m not really into these mathematical formulas... mathematical formula
http://electronotes.netfirms.com/s019.pdf



----------------------------------------
> From: idris1er at hotmail.com
> To: synth-diy at dropmix.xs4all.nl
> Date: Wed, 13 Jun 2012 05:27:06 +0200
> Subject: Re: [sdiy] Old unique VCO - Tune drifting problem - adapting a servo conversion‏
>
>
>
> It seems that I need something like -1V/-2V on the collector of the right-hand transistor at less to begin to create a waveform, I tried a lot of things but I can't get more than ~ -680mV ....
>
> > From: idris1er at hotmail.com
> > To: alan.needham at centrica.com; gergo_palatinszky at epam.com; synth-diy at dropmix.xs4all.nl
> > Date: Tue, 12 Jun 2012 06:15:16 +0200
> > Subject: Re: [sdiy] Old unique VCO - Tune drifting problem - adapting a servo conversion‏
> >
> >
> >   hi everybody!
> > I've tried the thermoregulating circuit from the Minisonic ! thanx Alan ;)
> >    It reduces pretty well the drifting pbm, with a good bias setting at the best I can get maybe  one 1/4tone up or down within 1h30~2h
> >
> >   So not bad result but not the solid as a rock stability, is it the servo convertion with a matched pair that could bring that?
> > I don't know how to adapt that kind of conversion on the circuit, here's the schematic :
> > http://img826.imageshack.us/img826/646/vco2shematic.jpg
> >
> > I've tried that without any result... :(
> > http://img337.imageshack.us/img337/1861/servow.jpg
> >
> >   I beg for your help S-Diy-list...  :)
> >
> >
> >
> >
> > > Date: Fri, 11 May 2012 17:56:10 +0100
> > > From: Alan.Needham at centrica.com
> > > To: Gergo_Palatinszky at epam.com; synth-diy at dropmix.xs4all.nl
> > > Subject: Re: [sdiy] Old unique VCO - T?==?windows-1256?Q?une drifting problem - adapting a servo c?==?windows-1256?Q?onversion‏
> > >
> > > The PE Minisonic had an oven as an option.
> > > http://www.timstinchcombe.co.uk/synth/pe_mini/pe_mini_feb_75.pdf
> > > Circuit on magazine page 145 (pdf page 6 of 7)
> > > I remember it taking about a minute to settle.
> > >
> > >
> > > -----Original Message-----
> > > From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Gergo Palatinszky
> > > Sent: 11 May 2012 15:49
> > > To: synth-diy at dropmix.xs4all.nl
> > > Subject: Re: [sdiy] Old unique VCO - T?==?windows-1256?Q?une drifting problem - adapting a servo c?==?windows-1256?Q?onversion‏
> > >
> > > Hi,
> > >
> > > What about using a 3046(3086) and use one of the spare transistor inside as heater ... ASM-2 did this way if I'm right ....
> > >
> > > Br,
> > > Pala
> > >
> > >
> > >
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