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  #1  
Old 06-06-2015, 07:02 PM
Stoodio Stoodio is offline
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Default using a dual pot expression pedal

Hi everybody.
I just got 2nd MidiCPU to wire up another set of pedals. My 1st is a Hammond 1 octave that is a portable and the new one is from a Conn console that I gutted and basically only saved the pedal board, expression pedal, speakers and case. This ex. Pedal has 2 pots inside with a toe switch (momentary toggle to position 2, rests at position 1). I had an idea that I could wire the two pots wipe signals to ct 22 and 23 and have that toe switch flip between the two, thus having both a crescendo and swell action on one pedal. What happens though, as many of you probably know, but I'm learning as I go, once the wipe is removed from the ct, the action goes to the maximum value (or minimum depending on the software setting). I also tried removing the 5v regulated signal but no difference of course because that still results in removing the wipe. I thought I'd throw it out to you and see if anyone might have an idea on how to do this. Thanks for any insight.
Thanks also to John for a great line of products and providing some of the best customer service via email that I've ever experienced.
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  #2  
Old 06-08-2015, 02:50 AM
Stoodio Stoodio is offline
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Default update and another question

So I wired up one pot to the midiCPU and tested it, then installed it in the pedal linkage... which only moves the pot 1/2 of it's range, so i get 0-2.33 instead of 0-5. grrr. Never dawned on me that the travel wouldn't be full range. Now I wonder if the two original pots worked in tandem somehow to get the full range. I really don't know what to do now so if anyone has come across something like this and can offer any insight I'd be very grateful.
I've given up on the toe switch toggling between two modes and just wired it to a ct to use later for a stop or something. would have a been cool feature but I'd be happy just to get a properly working volume pedal. Here's a picture of the pedal before I removed anything, in case anyone is interested. http://forum.highlyliquid.com/pictur...4&pictureid=62 Thanks again.

Last edited by Stoodio; 06-08-2015 at 02:56 PM. Reason: picture
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  #3  
Old 06-11-2015, 03:17 PM
Stoodio Stoodio is offline
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Default

no love for my weird pedal huh? ;-). FYI for anyone interested, it turns out both programs I use can be adjusted for the travel of the pot so that's good.

If anyone has advice on Sysex programming the pedal board for -2 octaves permanently (program each note down 2 octs, or a global command) that would be good. Maybe I should start a new thread on that topic though.

Last edited by Stoodio; 06-11-2015 at 03:25 PM.
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  #4  
Old 06-12-2015, 02:42 PM
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John John is offline
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Default

Check out one of the many op amp tutorials on the web that will show you how to scale your voltage from 0..2.3 V up to 0..5V. You'll want an op amp in a "non inverting amplifier" configuration.

I like part MCP6002.
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  #5  
Old 06-12-2015, 05:18 PM
Stoodio Stoodio is offline
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Great! thanks John. looking at one now.
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