Need help with a volume pedal that uses 2 potentiometers

[Dave Toce]

Hi all. I gutted an old home organ build a virtual pipe organ and want to use the original volume pedal but it's weird. It has a linkage on the left and right with a pot connected to each.

I bought a new 10k pot to use with my controller pcu and wired it up just fine. Supply voltage is 5v, wipe goes from 0-5 respectively.... except when installed in the pedal, because the linkage only allows the pot to rotate 1/2 way. So my thinking is that the mfg (Conn) used the two pots somehow in tandem so that when the 1st pot reaches goes from 0 - 2.3 and the 2nd pot's starts at half up going from 2.3 - 5 volts.

I could be way off here but I am hoping someone can help with some insight. The output from the pedal can only go to one control terminal on the cpu so it has to be combined. Here's a picture of the pedal
http://forum.highlyliquid.com/picture.php?albumid=14&pictureid=62

and a picture of the control pcu reference. It's exactly how I wired the single pot.
http://forum.highlyliquid.com/picture.php?albumid=14&pictureid=66

I may have spewed too much info so i apologize if so. Nutshell- can two pots be used to achieve 0-5 volts with each only rotating half way?. Thanks so much for any help you can give, guys.

 

[Arouse1973]

Hi Dave
Does the pedal have two outputs? I have seen two separate pots before, one for each channel. BTW I couldn't see your pictures for some reason.
Adam

 

[Dave Toce]

Hi Adam, thanks for the response. Sorry about the pictures I'll try to post them here. I think originally the pedal had two outputs, or maybe more but the pcu I'm controlling with it only has one signal for the wipe voltage. I fear I might have to modify the linkage to get the pot to rotate it's full range :-/

 

[Arouse1973]

Thanks Dave, not 100% sure but looks like it might be one POT for each channel. Why does it need to go to 5 Volts?
Adam

 

[Dave Toce]

Hmm, i didn't think about it going to two channels and the amp in the organ definitely was because it also had a rotary speaker so that makes sense. I thought it would need 5 volts because of the software. I used a test program and holding the pot in my hand I'd get a program change value from 00 to 7f or something like that. But after installing it in the pedal, i would only get 00-3g which I figured is the digital value of 0-2.3 volts. So I'm afraid the virtual volume pedal in my software may only go up half way, although it may be able to be calibrated. I haven't tried that yet but will look into that possibility.

 

[Arouse1973]

I guess your using the A/D port for this. If you are able to set the A/D reference to 2.3 Volts then that should work.
Adam

 

[Dave Toce]

Thanks Adam. Yeah it seems that may be my only option. Its a midi controller pcu and the control terminals can be set either to logic or analog so yea, a/d. I'll email the mfg to see if changing the ref voltage is possible. I appreciate the replies!

 

[Dave Toce]

Hi Adam,
turns out that both virtual organ programs I'll be using have the ability to adjust the min and max values which will work out fine. Thanks for your help though. Your suggestion that the two pots are for 2 channels kind of kicked me past that road block. I was hung up on it and over thinking it. Have a good one.

 

[Arouse1973]

Hi Adam,
turns out that both virtual organ programs I'll be using have the ability to adjust the min and max values which will work out fine. Thanks for your help though. Your suggestion that the two pots are for 2 channels kind of kicked me past that road block. I was hung up on it and over thinking it. Have a good one.

Glad I could help!
Adam