numbernone
Joined: Aug 16, 2006 Posts: 477 Location: new york city
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Posted: Wed Apr 14, 2010 10:22 am Post subject:
Switching jacks in JH designs |
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I am planning to incorporate a bunch of JH stuff into a standalone unit, and have a pretty general question that might apply to lots of other things as well.
Many of the jacks are of the switching style, often times closed to ground. As I am going to be using bananas, I am wondering where this might present a problem? Should I expect some instability if I leave an input hanging ungrounded? I would really hate to have to add a ton of extra switches to something like the Filter/Phaser as it already has so many.
Thanks! |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Thu Apr 15, 2010 1:29 pm Post subject:
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I've built the Living VCOs, Filter/Phaser, Tau Phaser, Polymoog Resonator, and Solina Chorus without switching any inputs to ground, and they all seem to work fine for me.
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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jhaible
Joined: May 25, 2007 Posts: 2014 Location: Germany
Audio files: 24
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Posted: Fri Apr 16, 2010 12:46 am Post subject:
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The Peasant wrote: | I've built the Living VCOs, Filter/Phaser, Tau Phaser, Polymoog Resonator, and Solina Chorus without switching any inputs to ground, and they all seem to work fine for me.
Take care,
Doug |
I never tried to leave things open, but with reasonable lenght of wires I don't expect a problem.
There are a few exceptions, though.
Sometimes I have LFO rate and depth CV inputs that allow the connection of a simple (passive) potentiometer as an alternative for applying a control voltage. Don't ask me *which* inputs on *what* modules that applies to (I would have to go thru all schemos again, myself); but you can easily detect this from a "pullup" resistor of 100k or 200k or something like that, connected from the input to +15V. The idea is that connecting a variable resistor (potentiometer) to the jack, the CV is created right in place. And for CV = 0 you need Resistance = 0, so normalizing the input to GND via the switch contact is what I did.
If you don't need that function, or if it gets in your way with banana jacks, simply omit the pullup resistor.
Jh. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) |
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