Expression Jack Switching

[rthryhorysak]

Is there a way that I can wire up an expression jack input that can control 2 different pots with a switch? So in one position it controls one pot and the other controls a different pot.

[armdnrdy]

I would say that you can definitely switch between two pots but...is the circuit going to like you doing that.

In other words....depending on the circuit...it may not matter....some circuits...you may have to make changes to make it work properly.

What circuit and controls did you have in mind?

[rthryhorysak]

I wanted to use this circuit and switch between the feedback and delay time.

[armdnrdy]

I don't have much experience with the PT2399 but...I would imagine that when you remove the resistance form the VCO (pin 6) and DGND (pin 4) it will change the delay rate on the fly.

There is a minimum resistance of 2.7K so that the VCO pin to ground doesn't get below that value.

The only way to do this is maybe with a rotary switch.
You can switch the pot to "Feedback" and have predetermined resistor values for the delay rate.

If I may...why do you want use one control for two parameters?

[rthryhorysak]

Well what I meant was to have only one expression jack input that would control one parameter, but I could then use a switch and it would control a different parameter. And leave the first parameter alone to be controlled by the normal on board pot and visa versa.

[armdnrdy]

Got it.

Your needs can be accomplished with a rotary switch. Doing it on the fly with a footswitch would be much more difficult.

I have been experimenting with a circuit using CMOS switching which allows the user to switch in the expression pedal in place of different controls. (rate pot and manual sweep)

The circuit consists of a momentary footswitch, CD4093, CD40193, and CD4052 and various passive components. It is not a small circuit! I'm sure it can be accomplished much easier with a micro controller but...I have never entered the realm of programming. Maybe one day.

I've had good results with the CMOS circuit but then got side tracked by other things.

Edit: I forgot to mention...this CMOS switching circuit is not "one size fits all." It would have to be "tailored" for each circuit.

[MrBinns]

So i drew this up:



It needs verification though.

The left most circuit would be the delay pot and an expression jack. The middle is for the feedback pot. The right is combined, what you are looking for.

The switching part could be any 6pol 2 pos switch. I used 2x 4pol 2pos switches and overlapped them because I didn't want to make the part. You could use active switches like armdnrdy said or a rotary switch. Check out the 4053 switch. It has 3 spdt switchs so you would only need 2 4053's.

The female jacks used are the kind that disconnect two pins when a male jack is inserted. So TN and T would be connected without a cable plugged in.

I hope I'm making sense. I kinda rushed making the sch. so sorry for it's ugliness.