Turning a footswitch into an ABY

[Shlafenflärst]

Hi everyone !

I'm new here, and new at building my own stuff. So far I only did a passive volume box. Also English is not my native language, so sorry if some technical terms are wrong.

A long time ago I bought a Laney footswitch for my multi-effects pedal, which didn't fit (it has on/off switches and it should have been momentary ones), and I actually don't need it. I tried selling it, and then put it in a box somewhere and forgot about it.

But the other day I had an idea : two on/off footswitches with LEDs that tell when they're activated, that's exactly what I'd need to build my own ABY pedal. I'm thinking of using the original PCB with the footswitches on it, and adding one volume pot per channel, and a ground lift toggle switch.

Here is the PCB :



And here is a drawing I made of it :



So I have several questions.

First, the DC jack has a third connector, which is usually used to bypass the battery when there is one. But here, there isn't one. It's connected to the purple track with the two diodes in the bottom, and I have no idea what it does. What do you think ?

Next, the green track that goes between the jack ground and the two switches is connected to the DC ground, and that's an issue, right ? I didn't think of using it as ground track, I thought I would connect it to the input jack, and connect the red and brown tracks to the output ones. The ground would be connected with wires. Am I right ? In that case I guess I should get the LEDs out of the PCB, which complicates things a bit, but that's OK.

Now about the volume pots, I'll probably use CTS ones, and I'm guessing logarithmic, right ? And which resistance would I need ?

And finally, the ground lift switch : can I simply put an on/off switch on one of the ground wires, or does it need to be activated only when both channels are active ?

Thanks in advance !

[iainpunk]

what i suggest you do is as following:

take the two swithces out ot the board and wire them from the ground up, this circuit board is to specialised for its purpose to reuse it as an ABY board.

i added the volume controls with MS Paint

[Shlafenflärst]

Thanks !

Now that you mention it, that might be the best option. The main reason why I wanted to keep the PCB was because it held the LEDs in place, but since I have to remove them, there's no real need for it. I also realise the diodes are completely useless, I'll keep them for something else. So here's my idea, what do you think ?

[iainpunk]

first of all, sorry i forgot to mention: welcome to the forum

euhm, yes that looks like it's right, and it should work.
there is one thing about your drawing, there is an unspoken rule that you have the input on the left side of the drawing and the output on the right side, the exact opposite of how pedals are, haha

[duck_arse]

also welcome, and nice elephant.

I think you [and iain] need to rotate your footswitches 90 degrees - use you meter to check which pole is which.

[Shlafenflärst]

first of all, sorry i forgot to mention: welcome to the forum

also welcome, and nice elephant.

Thanks !

there is one thing about your drawing, there is an unspoken rule that you have the input on the left side of the drawing and the output on the right side, the exact opposite of how pedals are, haha

So it's like you see the pedal from under it, right ? Actually makes sense, I'll try to remember that.

I think you [and iain] need to rotate your footswitches 90 degrees - use you meter to check which pole is which.

Yes, obviously I was gonna test it before soldering it. But thanks for mentioning it !

[iainpunk]

also welcome, and nice elephant.

I think you [and iain] need to rotate your footswitches 90 degrees - use you meter to check which pole is which.

if the switches in my drawing were wrongly oriented, its not my fault, they already were like this when i stole the drawing off of google

[Shlafenflärst]

Having burnt my fingers a bit and soldered the braid to the PCB several times, I finally removed all the parts. I think I'm getting better at this.



I have some spare components, I'll even keep the PCB, though I have absolutely no idea what to do with it...

Now I have to wait for my pay to buy some parts and equipment. See you in a couple of weeks ! And thanks again for your answers !

[patrick398]

I know this kind of defeats the point but if you're ordering parts i'd definitely order another couple of foot switches. I wouldn't trust them after a long de-soldering session

[Shlafenflärst]

Is there anyway to test them before buying new ones ?

[patrick398]

Multimeter on continuity test to see if the middle pins are throwing the contacts up and down when you hit the switch. The issue with heating switch lugs for a long time is that the epoxy that secures the pins in place melts and they lose contact. Did you notice any of the pins moving whilst you were desoldering?

[Shlafenflärst]

Thanks. I'll test that when I can buy a new multimeter, I lost mine. I'm not sure but I don't remember seing the pins moving. At least they don't move now.

[Shlafenflärst]

Guess who's back !

I just got my new multimeter, I tested the switches, they seem to work. There is a resistance of about 0.5 Ω between the contacts, is that acceptable ? (serious question, I'm new at this, I have no idea)

[antonis]

There is a resistance of about 0.5 Ω between the contacts, is that acceptable ? (serious question, I'm new at this, I have no idea)

More than acceptable, taking into account 0.2 - 0.3 Ω for DMM probes resistance..

[Shlafenflärst]

Great, thanks !

[Shlafenflärst]

Hi everyone !

Back here with a new wiring pattern : I removed the pots, thought they would be unnecessary since there are gonna be plenty of volume pots on the various effect loops. Also, since I intent to modify the electronics on one of my basses with a Rickenbacker style stereo output, I wanted my ABY box to also allow me to split the stereo signal in two mono signals. In that configuration the footswitches would be redundant with the pickup selector on the bass, I could do something to bypass them in stereo mode, but I'd like to keep it as simple as possible so I'll just leave both channels on when I use it with the stereo bass. Here's the new wiring pattern :

I'm concerned about the ground lift. I know it will work when both channels are active, but what about when only channel B is active ?

Thanks in advance !

By the way, I found the enclosure :