A-B-C-D Signal Pedal

[Nobisayzhoi]

Hello, I'm looking to make an A-B-C-D switch with LED indication, but don't know how to make one, could someone direct me to a schematic that could help me?

[Sooner Boomer]

You could build a circuit using an Arduino to do the switching in about 10 minutes. 

I'm a bit old fashioned, and would do it using a circuit called a ring counter.  In your case, this would consist of four flip-flops, wired so that the first one turns on when powered up, then when a momentary switch is pressed, the first turns off and the second turns on. Second press of the switch, the second flip-flop turns off and the third turns on, etc.  Do a google search for ring counter circuit.

To switch the actual signal, I would use a chip called a CD4016 quad bilateral switch.  It basically has four electronic switches inside it, that are activated by an external signal.

Build the circuit using CMOS flip-flops and you can power it with any voltage from 5 to 15 volts DC.  You need to be careful about static electricity when working with CMOS chips.  Building the circuit with sockets, then plugging the chips in when all the wiring is done is a good idea.

Look up the stuff I've mentioned.  If you have more questions, I'd be glad to help.

[ElectricDruid]

Rather than build the counter yourself using flip-flops, you could use a ready-built counter on a chip, like the 4017 decade counter:

http://www.learningaboutelectronics.com/Articles/Decade-counter-circuit-with-4017.php

As the name suggests, this has 10 outputs, so you could do an ABCDEFGHIJ pedal if you wanted to! But you don't have to use all the outputs if you don't need them, and it's easy enough to make it cycle through four - just feed the fifth one back to the reset pin.

HTH,
Tom

[Ben N]

IIRC, Paul Nelson had posted a complete project, with schematic and PCB layout, doing exactly this, and with a bonus of a sequencer option to cycle between the loops. But I don't know where to find Paul's stuff anymore. [Edit: Here ya go: https://sites.google.com/site/electroconducive/sequentiallooper.]
Also have a gander at: url=http://hammer.ampage.org/files/quadsequentialswitch.pdf]http://hammer.ampage.org/files/quadsequentialswitch.pdf[/url] for an older but AFAIK still doable all-CMOS version of this, although it is designed for modular synth application (+/- 9v power) and would need to be modified for stompbox application.
Both of the above are 4017s controlling 4066 switches.

[Nobisayzhoi]

I'm a little confused, how do I wire a 4017 decade counter to a guitar signal?

[Ben N]

You don't. You wire the 4017 to a momentary switch and a 4066 (or, if you want real true bypass, a set of drivers and relays). All the 4017 does is trigger the switches to open and close. Look carefully at the schematics. It might also be helpful, just to understand what is going on, to read some of the articles on effects switching at Geofex, like this one about switching with another CMOS decade counter and multiplexer.

BTW, as ED says, the 4017 can handle more loops. The probably useless sequencer in Nelson's design could easily be traded for two more loops (A-B-C-D-E-F), just by adding one more cheap-as-chips (yuk, yuk) 4066, and some jacks and resistors. (BTW, the 4049 is just an LED driver; it doesn't do any of the actual work.) I just noticed that his schematic is missing a lot of parts values, although those can probably be figured out and probably aren't terribly critical.