[sdiy] dual vco

[Scott Gravenhorst]

Ian Smith <taciturn_unquiet at hotmail.com> wrote:
>
>Is is necessarily a bad thing if the two VCOs are synced? I mean, 
>if you're planning on syncing them (and personally I find it to 
>be an interesting sound) wouldn't it be good to have this "built 
>in" sync? 
>
>just my US$0.02
>

Having had this problem with a FatMan "soft synch" - it's one thing to synch VCOs when one _wants_
them to synch.  There are often times when one does not want synch, like for fattening a VCO sound,
it's common to tune them very close together.  If they synch up, the fatness is lost.  

>
>> I've tried to use two sections of the same chip in two different
>> VCOs. They usually sync and it cannot be completely avioded, as they share
>> "real estate" and especially power pins. Decoupling the power supplies
>> is not effective in fixing the problem.
>>
>> Even the 4013 might be affected. There is a "CMOS Theremin" that uses
>> 4093 gates as oscillators, they MUST be in different packages or they lock
>> for sure (a fatal flaw in a theremin, na ?)
>>
>> H^) harry
>>
>> ----- Original Message -----
>> From: Ian Fritz 
>> To: Synth-diy at dropmix.xs4all.nl
>> Sent: Thu, 8 Apr 2010 10:03:49 -0400 (EDT)
>> Subject: [sdiy] dual vco
>>
>> Has anyone made a pair of VCOs using dual chips? I have one running using
>> LM13700, TL072, CD4013, etc. The two oscillators sync up a bit, and I'm
>> not sure if this intrinsic or due to still being on a whiteboard.
>>
>> Ian
>>
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-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- FPGA MIDI Synthesizer Information: home1.gte.net/res0658s/FPGA_synth/
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