Relay-controlled true bypass looper with overkill features! (pics and schematic)

[aion]

You know those projects where you just keep adding more and more features until it's ridiculous? I started out wanting to build a true-bypass looper strip and ended up with a monstrosity. (A good one, but wow.) The problem is that I change my mind so often that I needed to build something that was flexible enough to accommodate anything I'd ever want to do. Let's hope I got it, because this is a pretty massive project.

I'm a big fan of Jack Orman's relay microcontrollers and used them as the basis for this project. For starters, here's the schematic of the building block - then I'll explain what everything does.



"DEF" is a switch that controls whether the loop defaults to on or off when it first powers up.
"LINK" is a switch that allows you to link this channel with the next one, so that one switch tap controls both channels. You can set up an A/B loop if you link the channels together and one of the channels is out of sync with the other (via the "DEF" switch).
"MOM" is a 3PDT switch that converts the loop into a tap tempo via the Send and Return jacks (can tap for two pedals at once, or more if you link it with an adjacent channel). It does this by cutting power to the board and then connecting the SEND and RETURN jacks directly to the switch (through blocking diodes to prevent unwanted interplay between the pedals).

B1/B2 is a bypass jumper. If you're building a true bypass looper then this should always be connected, but if you just want the relay to act as a normal DPDT switch, you can leave this jumper off and connect B1 and B2 to another set of jacks or something. (this would be useful for an A/B loop that only takes up one channel)

It's designed to be modular, so you can chain together as many of them as you like. My looper will have nine of them.

By using relays, it can do some pretty cool stuff that normal switches can't, due to the channel linking. Here's an example: I have an EHX Superego which has an effects loop. The loop lets you do some cool stuff to the frozen signal, like tremolo and modulation, and still play over top with the dry signal. But I don't want all those modulation effects only available to the Superego, so I'm setting up two of the channels to act as an order switcher - by tapping a switch, it moves the modulation chain either inside the Superego loop or after its output. This requires a couple of Y-cables to accomplish, but otherwise it's an A/B setup. (This could be done with a 4PDT stomp switch, but wouldn't have an LED indicator, which is a dealbreaker.) I also have a volume pedal that I want to move in and out of the loop, but I want it to be independent from the modulation chain, so I'll do the same thing with that.

The build is still very much in progress, but here are a couple of pictures of the test fit... the enclosure will still need to be painted, but it's going to be built into a pedalboard so that's why it's open on one side. It's 0.1" aluminum that I took to a metal fab shop in town to bend it for me.







It'll be a couple of weeks before it's all finished, so I'll post more pictures when there's something to look at.

[nate77]

That thing is a beast Kevin! I'm gonna give this a shot after I wrap up my current project. I'm noticing a pattern with your designs and layouts, an insatiable need for flexability. I love it. Do you plan on having a batch made up and putting them up on your website?