This is a project that I developed about 2 years ago for a rack amp system I was working on that has been put aside for now, so I decided to adapt the circuit for pedal use since the programming for the micro had already been done.
This is a 1″ x 1″ pc board which holds an AVR microprocessor that is controlling a latching DPDT relay. The LED indicator on the pedal is also driven by the micro. The soft-touch momentary switches that are shown several posts below were bought for this project.
You can use the pcb to build a new pedal, or retrofit it into a Boss or Ibanez box to give them true bypass.
More info is available here.
AWESOME!!!!
Just a note here… the “Two LEDs on 1 AVR line” idea that is shown a few posts back was used with this bypass system in the rack prototype I was developing.
A simple mod to the bypass board allows the idea to be used with it in a stompbox.
great stuff! and the price is totally right as well. 7 bucks w/ the chip? can’t beat that. now i can grab some really nice vandalproof switches, and never have to replace 3PDTs again!
Jack,
Have you considered licensing the programming that you have done on the AVR-microprocessor so that other pedal builders could incorporate the features into single board finished products? Then you derive a return from the development efforts for those who can otherwise source the parts for a unified board level product. I am not currently a commercial pedal builder, but it occurs to me that there is an opportunity here if you wish to pursue it.
I would be glad to offer the pre-programmed microprocessor in quantity at OEM prices to any builders who want to incorporate the relay-bypass into their pedal.
In a post at DIYstompboxes, someone is intentionally trying to mislead the members into thinking that the AMZ relay bypass is a copy of some other switcher. This is ridiculous, as the AMZ bypass relay design is the only one that is using an AVR microprocessor, as opposed to the PIC micro that is used on the two other bypass pcb designs that I know about. This also means the number and type of components are not the same, i.e. different circuit design, and the pcb parts layout will necessarily be totally different.
As far as I know, my design is the only AVR-powered true bypass relay system.
Just for clarification…
Hi!
So how hard would it be to retrofit this into a boss pedal? Would it fit in the battery area?
Thanks!
- Dave
Dave,
I have not tried it yet but it should be simple. Not sure where it would fit but I probably would not put it in the battery area in case you had to use the pedal on battery power one day.
regards, Jack
Do you think that this could be adapted to work with the Rockman Octopus as a remote trigger for stomp boxes?
Nice, and opens up a ton of possibilities – although couldn’t one achieve the same with CMOS logic? Also, one should be careful with that micro’s current sourcing capability…
What happens if the pedal looses power? With a mechanical switch, I could stomp it for bypass, but with this circuit once power is gone there seems no way to toggle to bypass.
I have some Hardwire pedals that use a relay but when they loose power they automatically toggle to bypass mode (presumably this means more power is used when the FX box is engaged though).
If the pedal loses power, the bypass relay remains in the position that it was in when the power loss occurred, since this is a latching relay.
Non-latching relays will switch to their default position on power loss, which would usually be the bypass condition, but the trade-off is that non-latching relays require a constant application of power to hold them in the active mode.
The AMZ relay board uses the latching relay so that much less power is needed to control the bypassing.
Consider that the jfet switching system in Boss and Ibanez pedals will pass no signal at all upon power loss, no matter what condition the bypass was at the time. If you lose power to your pedalboard, it’s time to pull the power plugs and run off batteries until the power supply can be checked out.
I was wondering; Is the switching relay an dedicated ‘low signal’ switcher ?
Kind regards
and compliments,
H.C. van Ernst
Nice. I have used this method with a Atmega168–
But I have recently been using a plain old 555 timer with an optical isolator instead of a transistor.
You can also use a dual 555 (LM556) to run 2 relays which is nice for routing signals to separate amps.
I have a schematic if you want it.
can this function at 18v?? what if i want to put it into an 18v pedal?
Hey, can you send a pulse to 2 or 3 of these guys from the same footswitch at the same time? how many could you run at once using a power supply like the dunlop dc brick? thanks!!!
Yes, you can pulse as many of them as you need with one switch contact. Instructions are included in the support material that is provided with purchase.
The idle current is quite low, and it is only drawing 30ma or so (total) when the relay is pulsed, so a large number could be powered by the Brick.
-Jack
Everything I am using is contrlled by MIDI except for a single DIY pedal which requires a 3PDT switch.
Would I be able to use a Boss FS-6 Dual Footswitch (Latch or Unlatch), the switch function from the Beringher FCB1010 or even an ENGL Z-11?