Can I build a VOX VT20+ Footswitch? Is it possible?

[daryl]

Is there any way to build a foot switch to switch between the user saved presets?

Like this:

[senko]

Yes, it's possible.

You will need one on hand to take apart so that you could see what's actually going on inside the case.  I haven't researched it, but the circuit could be very simple (switch + wiring + plug).

Post pictures if you actually take it apart. 

[daryl]

I found this schematic:

http://www.whitelamp.com/public/vox_vfs5.html



Which is a good starting point...

Its the right footswitch but being used with the wrong amp, mine is the VT+ range with 3 banks and this is talking about the VT range with only 2 banks.

[daryl]

I found some more good info here:

http://www.valvetronix.net/forums/leds-on-vfs5-t3247.html

[daryl]

IC Chip info:

http://www.ti.com/lit/ds/symlink/tlc352.pdf

[daryl]

[senko]

You've got all that you need to start building it.  What questions do you have for us to help you with?

[daryl]

I found most of these after I asked the question.

But I still have to find a PCB.

Also I'm trying to figure out a stripped down version that does not have the bank change but just swaps between 4 presets.

[senko]

So, here's what I got:

And here are my notes (don't take these as 100% accurate):
That dual differential comparator IC configuration isn't necessary for anything other than lighting up LEDs.  The comparators are biased at ~1.5V and the Bank Switch toggles between each of the comparators, switching one LED from Green to Red.

In this crude schematic, you'll notice I got rid of the bank switch.  Now your presets are selectable.  This may not be what you want, but test and try.
R11 was moved down next to the transistor, which shows the voltage divider biasing of the transistor in action.
R12 and C1 look like a low pass filter used to smooth out the transients from the Bank Switch bounce.
R13 and R4 can be combined together into one resistor, as they are in parallel.
This is the 3.3V voltage regulator datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/111555/ROHM/BA033T.html
The regulator received voltage through the Tip connection of the Stereo plug/jack. 

If you need any other help, just let us know. 

I'd suggest getting some prototype PCB, match the components from the pictures to the schematic, and then build one up to test. 
You don't need a stomp switch right away, so any switch that you have will be good.

Good luck!