[sdiy] Adding offset to vactrol??

[Dan Snazelle]

I have been playing around with vactrols. VTLC53's and clm6000's. I would like to use them with CV sources. I would like to be able to add some offset of some kind so that i can get around 2 issues:

1. they dont start reacting until a certain voltage ( is it 2 volts?)-is there a way around this?

2. they stop reacting when being driven by a high frequency from a vco or lfo. (not that high a frequency either. the led just STAYS on. for example is there a way to add an offset so that the vactrol thinks 1khz is actually 350 hz -this is just an example but i'd love to be able to actually have the vactrol send out a cv that can follow a vco from very low to very high.


any help greatly appreciated!!

thanks








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> From: czvekan at gmail.com
> To: Synth-diy at dropmix.xs4all.nl
> Subject: Re: AW: [sdiy] Prophet 600
> Date: Mon, 2 Jun 2008 22:24:58 +0200
> CC:
>
> Thank you Pete and thank you Bob,
>
> I have looked at both of your Prophet 600 Schematics. But I already
> had those exact ones. The Board 1 and Board 2 are not scanned and not
> covered. And unfortunately I was interested to look at Board 1 schema.
> That's where the Potis and Switches and so on are. I am having some
> difficulties narrowing down the problem. I have some weird behavior
> with Voice 3b . Ever since I replaced the DAC71 and tweaked on the
> R4333 something happend and I don' t know how to adjust the poti
> properly . Sometimes I think I have it just to realize that this VOICE
> 3b is of in the last octave but only if I have frequency>6 - 10. I
> have replaced U423 thinking the OP-AMP might be bad, Then I replaced
> U416. Tomorrow I will replace the CE3340 just the see if maybe that is
> Bad . But I doubt it it the .I suspect some 4000 series CMOS on Board
> 1. There are a few. That demux the frequencies of VoicesA and VoicesB
> and fine tuneB.
> I think I'm gonna order the Technical Manual straight from
> WineCountrySequential. It's like 24$ but oh well. I can't be that
> cheap :).
> I will need in the future and synth deserves it.
> So thank you again you guys been very nice and fast in helping me.
>
>
> Csaba
>
>
> On Jun 2, 2008, at 9:41 PM, Ullrich Peter wrote:
>
>>
>>> Does anybody have the Prophet 600 Technical/Service manual as a pdf
>>> or file ?
>>
>> Just for information: I already sent him the schematics today per
>> private email.
>>
>> Ciao
>> Peter
>>
>> http://www.ullrich.at.tt
>>
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