Gadget Fuzz

[chuckyshorts]

Hey guys!
I am waiting for a couple of Gadget Fuzz (ZVEX Machine) boards. I was planning to make a dual/"stereo" version, and was wondering if someone more experienced than me could give me some pointers when it comes to the footswitch part.

I was hoping that I could use a single switch to activate both channels via relay bypass board/s for more silent switching. Specifically these from Parasit:

Relay Bypass PCB

Parasit Studio is a recording studio and diy stompbox resource with vero layouts and original designs

www.parasitstudio.se

Is this possible? If no, well dang. If yes, how exactly? -and is there also a way to add a second momentary switch to actually activate the effect momentarily?

If anyone here has any experience with this circuit and would like to share their any insights it would be much appreciated. Thanks!

 

[fig]

Will you have two inputs, or just two outputs?

 

[chuckyshorts]

Two inputs and two outputs

 

[fig]

Using that pcb, the signals would merge at both input and output, and I don't think that's what you want. I'm guessing you want autonomous signal paths (channels).

@Robert has an intelligent relay board, but I'm not certain of the capabilities (I was moth-balled).

 

[chuckyshorts]

Hmmm, ok thanks anyway man. If its not easily doable, I could just use a 4PDT switch instead -right?

 

[chuckyshorts]

I guess I was hoping I could use two bypass relay boards and switch with some sort of dual momentary switch...

 

[jwin615]

I guess I was hoping I could use two bypass relay boards and switch with some sort of dual momentary switch...

Necro, but incase you havent worked this out already...
you absolutely could. need to use a momentary dpdt switch like this

DPDT Momentary Foot Switch - Solder Lug

Same day shipping and awesome prices for guitar pedal parts! A family owned business with AMAZING customer service.

lovemyswitches.com

Wire 2 seperate relay boards, either the ones you linked or PPCB basic(not intelligent) relay bypass boards and connect them to independent side of the to the NO side. well, I know for PPCBs board it would be the NO side, not sure about the parasit as there's no schematic in the build doc. It may use the NC side as its transistor switching and I'm unsure how that implemented. Assuming its the same as the tagboard here:

Relay bypass without a microcontroller

I've seen alot of people wanting microcontroller-free relay bypass boards. There's a few designs out there, but most of them seem overly complicated, so I designed this one. It uses two 2N3904 as a...

www.parasitstudio.se

then it would be the normally open side.

On another note, You'll have to take care to really match your components to have both sides sound very similar. how close you need it is in the ear of the beholder. For a stereo guitar rig, probably not a huge deal but if you were to be using this for more detailed work, say parallel processing a drum bus, gonna need to match closely. The other thing I would watch out for is if you are using dual layer pots(so 2 circuits with one set of controls), probably need to check them closely as they can vary wildly from pot to pot(up to +/- 20%, depending on the make). Since they are all linear, you could get larger value pots and run resistors in parallel to match them more closely.

BOURNS PTD902-1015P-B502-ND are probably the best at a reasonable price that i know of, if you can find them.

 

[chuckyshorts]

Wow, thanks man, that really answered all my questions. And no, -I was still a little unsure about this and which boards to choose, so this was very, very helpful indeed! Thanks again, I really appreciate it

 

[jwin615]

Wow, thanks man, that really answered all my questions. And no, -I was still a little unsure about this and which boards to choose, so this was very, very helpful indeed! Thanks again, I really appreciate it

Sure. Hope it works out well for you.
One other thing to think about in this is grounding. I'm guessing you're using this in a stereo guitar rig. I'm not sure what the best practices for this would be to avoid any ground loop issues. I'm guessing it's one of the two:
1)fully isolated jacks and independent ground planes for each circuit with the enclosure grounded via the DC ground only.
2)a star grounding scheme where all grounds tie to a singular point(usually on or connected to the enclosure)

I would lean toward isolated circuits that only share the DC ground but not certain. My concern is having a loop created between channels somewhere else in the chain. Of course, this could all be much ado about nothing. If anything, I'd at least recommend, all else being normal practice, isolating your output jacks from the chassis and installing a ground lift switch for them. A sub mini single pole toggle, maybe positioned between or beside the jacks, that connects and disconnects the ground to them. If you have hum, lift the ground. The jack should establish ground via the next pedal. Or just wait and see if it's an issue first

Maybe someone else could chime in with their experience with dual mono builds and grounding. I worry about this stuff way more than it's worth.