freestompboxes.org

New to the world of relay/microprocessor based switching. A friend of mine is looking for an overdrive, distortion, and fuzz in one box. He wants three footswitches, and wants the switching to function as follows:

OD-on, dist-bypass, fuzz-bypass
OD-bypass, dist-on, fuzz-bypass
OD-bypass, dist-bypass, fuzz-on

Is there a way to accomplish this using one of the "true-bypass relay" boards from Muzique or Small Bear? I'm having trouble finding any examples or starting points for this. Any help is a big help! Thanks!

http://www.smallbearelec.com/servlet/Detail?no=1379
http://www.muzique.com/schem/dpdt.htm

Hey Crumbchildz, not sure if you're following this thread and if this is still relevant to you; you might want to keep it all 'oldschool' with a bunch of diodes and 3 bi-stable relays, all with one end at half-voltage of 4.5V. Three momentary DPDT's each switch one relay to ground and the others to +9V. You'll need the diodes to uncouple the DPDT's from each other.
No need for a microcontroller. What's missing is three LEDs, you'll need something like a millennium bypass LED on each effect.

I haven't tested it but I made a sketch and I think it should work. The 5V bi-stable relays from my IO-board will switch at 4.5V.

That said, if you wanna go all uP please go ahead

Drop me a PM if you're still interested and can't figure it out, I'll get an email that way so I can respond.

I would like to know more. I read your thread using the Attiny85 but if there is a way to do this without a micro controller, I'm all ears!

Something like this should work.

Switches are momentary, relay contacts are not shown. Depending on the bistable relays used the 4.5V might need to be buffered, to be able to supply enough current to make them flip. The bistables I use are DPDT, so no contacts left for the LEDs unfortunately...

Thanks for posting the schematic. I haven’t used relays before, see them a lot in uP setups and loopers. Do you have any brand/types you recommend?

I've used mostly Omron (G5V series) and Finder (30 series) relays, because I had a free source of used ones.

But this particular application as well as the IO board ask for a 'bistable' aka 'latching' relay, which means it only needs to be powered for a short time and then it stays in that position. Normal relays fall back to their NC (Normally Closed) position when you remove power. Either the direction of the power applied to the bistable or the contacts that you power determines the position it's switched to (depends on the type).

The bistables I use are the Takamisawa AL5WN-K, approx. $2 on ePay with free shipping. They switch with power-direction.

Also: http://en.wikipedia.org/wiki/Relay