Searching Looper 3-way with one-click-to-change

[Elijah-Baley]

I guess I have to try arduino.
If you know something I have to look about my project tell me.
I know I need an arduino. Ripthorn suggested me arduino nano, Slowpoke101 suggested me arduino UNO.
What other parts I need? I think Footswitch SPDT momentary.
Then, a  ready relays PCB, but I can't say what kind I need.
I have to take on count the current draw, I fear for relays.

[Ben N]

Get yourself a starter kit, and play around with it, get to know what it can do generally. Then find some code that works or is adaptable for your project (shouldn't be too hard), breadboard the hardware and write and test the code. Once you have it working that way, then you can think about how to implement the hardware for real.

[merlinb]

Arduino Nano plus a relay module large enough for your needs 4way? 8way?. e.g.
https://www.ebay.co.uk/itm/1-2-4-6-8-16Channel-Relay-Board-Module-Optocoupler-LED-5V-fr-Arduino-PIC-ARM-AVR/282571011217?hash=item41ca8b7491:m:mTb5fR4rzGtySZqzitoIa3g

[Ben N]

If what you are planning is an always on device (i.e. never bypassed), I would suggest forgoing the relays and going with CMOS switching, like a 4066 ($0.28 at Tayda) or 4053 ($0.31). The relays make more sense IMHO for a looper.

[Elijah-Baley]

Thanks Ben.
What kit are you thinking about?
CMOS could be ok, too. But doesn't it need relays, too? Anyway, I have to understand what I can use precisely: schematic, PCB or stripboard layout, made by me (am I so good? ) or found it somewhere (if there's any). I know some schematic, but I'm still confused.
My bigger difficult is to get, indeed, decide what schematics to use, what hardware, what PSU I need, what is the space I need.
I assume the box will be rather big because the 4 circuits and the space between the footswitches, but I think all the switching boards need a big space.

Thanks merlinb.
4way is enough, into the pedal there will be: 1) clean preamp, 2) overdrive, 3) crunch, 4) high gain. I decided four. So a four relays PCB shoudl be ok good.

[Ben N]

Kit?
I meant the switching itself. If you run a buffer into the inputs of your four preamps, a single 4066 would give you four switches to select your output, controlled by Merlin's circuit. No relays required, although you might need a little bit of extra circuitry to make the CMOS switches behave well with audio signals. Read RG's http://www.geofex.com/Article_Folders/cd4053/cd4053.htm.

[Ripthorn]

Here is how I would do it:

- Windows 7 PC, download the Arduino IDE
- Go to Ebay or Aliexpress and get an Arduino nano (less than half the size of the UNO). Can be had for about $2 USD each. I use the ones with CH340 chips with no problem, though you do have to download a driver for it (I have it somewhere and can send it along via email or something)
- Depending on how you implement it, I would actually use DPDT relays that do NOT latch. This will draw more power, but if you are using a wall power supply with analog dirt circuits, that shouldn't be an issue. The benefit of this is that you can connect the LED's directly to the I/O pin that feeds the relay, thus, if the relay is on, the LED will be on. On DPDT relay per circuit. I have a particular model that I personally like and have used multiple times, let me see if I can dig up a part number.
- One BJT per relay, along with one diode (1N4148 is fine), along with a couple resistors. I have some schematics from a related but slightly different project I did last year that I will see what I can dig up.
- The code. This is where you will need to do some learning, but at the same time, I have code that could be easily modified to exactly what you want, including the option of exclusivity switches like on the GigRig Quartermaster. It really is pretty straightforward if you have ever coded something before. If not, that's ok, we can help. I don't have time to sit and hash something out for the next couple days, but I will try to do so, as I have been thinking about doing something like this for a while, and it would make a fun project.

A couple of items to note:

1. The enclosure and relays will be the most expensive part of this whole project, with the relays being about $2 USD/ea and the enclosure being ~$10 (assuming a larger enclosure).
2. The loops will be in a fixed order. Making the loop order switchable is a more complex problem and requires a relatively expensive surface mount IC.
3. The wiring is going to be interesting. See my 5 loop, MIDI-controllable switcher here: https://scientificguitarist.wixsite.com/home/mls-5 for some inspiration. I made it so that any combination of loops can be used, though adding exclusivity switches ought to be pretty simple. Use smaller gauge wire for all the non-audio signals, as you will just be using 5V to signal when things should switch and to activate the relays.