[sdiy] Source for center tapped pots? Anyone?

[mark verbos]

The only problem with that is that you now need to add 2 VCAs. Well, you 
could run the envelope into the center pin and then the outer pins to 
the opamp inverting summer thing.

But, what about if you want to turn up one parameter with a turn to the 
left and a different one with a turn to the right? Then you need 2 VCAs. 
The oberheim SEM does this with just a center tapped pot. Also, center 
taps make the zero point exactly zero.

good luck,

Mark






john mahoney wrote:

>>>Me too!  I'd love to find some center-tapped linear pots that also have
>>>mechanical center detent.  Preferably in 50K or 100K values.  These
>>>      
>>>
>would be great
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>>>for +/- modulation amount controls.  The center tap would allow you to
>>>      
>>>
>get a
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>>>true zero point in the center.
>>>      
>>>
>> Exactly, I got the idea from the env intensity control on the VCF of the
>>PolySix which I think is a brilliant and powerful single knob control, so
>>    
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>I want
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>>at least one of these on my EG module and would need another dozen or
>>so elsewhere in the synth.
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>>
>[snip]
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>> I really only wonder about the price. If there's interest among other
>>listmembers maybe we could agree on a "standard type" and get a bigger
>>order volume for a better price. I was thinking about 200K lin pots with
>>the center tap so each half turn would function like a 100K lin pot.
>>    
>>
>
>
>Follow the clicking mouse...
>
>Peter Grenader designed a tiny little circuit for adding this
>inverting/attenuating function wherever you wish:
>http://www.buzzclick-music.com/gizmotron.html.
>Peter says, "The Gizmotron PCB was designed specifically for the same 50k
>linear Panasonic pots used by Blacet (Digikey part number P3T9503-ND)."
>
>So, off to Digikey for more info... Okay, here it is:
>
>Only 5K thru 50K values are available for these pots. 503 in the part number
>means 50K. Note that "-ND" does not mean "no detent."
>
>Digikey part P3T9503-ND has no detent.
>Digikey part P3R7503-ND is the same pot with a center detent.
>
>Hope this helps!
>--
>john
>
>P.S. The Mono/Poly has an "invertenuator" on it's VCF EG input, too. Yes,
>it's a great feature!
>
>
>  
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