Fender Twin Amp Footswitch

#1

Hi!

I was looking through my guitar gear and stumbled on my "Fender Twin Amp Footswitch"

I was wondering of this could be connected to an Axoloti. It would prove to be quite a handy thing I think.
I checked the service manual of the amp and it says the following:

_"A 27.5VAC signal is tapped off from the Brown secondary of the power transformer. This signal is presented to the Footswitch jack. By rectifying the positive or negative half of the waveform, a DC control voltage is created. This voltage is used to control several opamp comparator circuits."
(hard to understand for my knowledge)

Opening the unit got me these pictures:

IMG_1746.JPG3075x959 650 KB

IMG_1747.JPG3264x2448 1.26 MB

IMG_1748.JPG3264x2448 1.49 MB

I guess it will be difficult to directly use the mono jack output from the pedal without hacking in to the thing and 'directly' connect the 3 separate switches to the Axoloti?

Maybe somebody more electronic savvy can advise me whether looking deeper into this is worth the effort or whether I better just assemble some kind of pedal myself?

All input much appreciated!

#2

If you want to use it without modifications you'd need 27V AC from somewhere (perhaps a lower voltage would work too, but nothing as low as the 3.3V or 5V the Axoloti can provide). Then you'd need a few resistors to turn the signal into something the analog inputs of the Axoloti can use. Then some signal processing is needed, but the Axoloti ist good at that. :slight_smile:
(The signal woud be some asymmetrical AC: one half-wave is on/off, controlled by the reverb switch, the other would be 4 different amplitudes, depending on the other two switches).

If I wanted to use it for Axoloti only, I'd rewire it to be able to read all three switches via one analog input. That way, I'd make use of all the mechanical parts (case, switches, socket), because I'm no good at mechanical construction.