Arduino Programable 5 Pedal Switcher





Introduction: Arduino Programable 5 Pedal Switcher

Searching for a simple programable pedal switcher over the net I was
amazed about the overpriced gear around there... so I came out with DIY solution and found several great projects but found 'em too complicated (PCB etching...) or maybe too overpriced for my needs. All I needed at that time was the simplest possible programable true bypass relay switcher for 4 pedals but found a way to switch up to 5 pedals with the "nano" version of arduino UNO. With 2 Arduino nanos (thru serial communication) you can surely extend this as up to 8 switchers! (to see: second part of this instructable...). Posibility to add MIDI program change out on pin 1.

Addendum: connect a led in parallel of one of these little on the relay board (caution: check the polarity!). This manner you'll know which relay is on or off when programing. Tip: I 've used the hole of the screw near the inboard led to drill thru the chassis and put it the parallel one on. (see pictures on my second instructable )

After noob searching for the "code-part" of this project over internet and spent hours and hours of led debuging (hey, I'm NOT a coder, just a r'n'r guitar player!) I got out with an amazing library named "keypad.h". Initially intended to manage secret code doors within a keypad, we'll see how simple is to "fool" the code with a 3 way selector, so with only 5 momentary switches we'll can access up to 15 functions and store 5 presets on internal EEPROM! The hardware parts are current sees over Ebay / Google so please don't ask me "how and where can I buy this thing or this other..." ! Google is your friend and Ebay too!

Caution: some noise issues where experienced by some builders (me included). I suspect those cheap and chinese relays aren't made for audio signals. The ideal relays should be some called DPDT but for instance few advices can be followed: use shielded cables all along the signal path, ensure all the circuit in a metallic box use caps (usually 10u) for decoupling and/or add some high resistances to all in and outs jacks. Adding a booster pedal in front of the input may strongly reduce these noise...



-position "A" (select switches) from the selector (cases 'a' 'b' 'c' 'd' 'e' on the sketch) -> select wich pedal to loop ON (1,2... 5). When finished, turn the selector to ->

-position "B" (preset memory mode -cases 'f' 'g' 'h' 'i' 'j') -> select the number of the preset (1 to 5) where you want to preserve the loops (the led of the preset you choose will lit 2 times. Caution: don't press the switch more than once because you'll reset the preset (all ' 0,0,0,0,0')!

-Rotate the selector back to position 'A', select another pedal combination and store it on next free preset on position "B". You can repeat this procedure 5 times. Once you have your 5 combination stored, rotate to->

-position "C" (cases 'k' 'l' 'm' 'n' 'o')-> read the preset (1 to 5) you memorized previously

-enjoy the art of rocking pedals with one footpress !!!

see more hardware pictures made by some followers and me

Step 1: Arduino Programable 5 Pedal Switcher

So here are the parts:

-1 x arduino Nano with Atmega328 built-in (~4 to 5$)

-1 x 9v to 18v / 3 amp power supply (~10 $)

-1 x LM7805 or alike

-3 x ways rotary selector (~4$)

-5 x SPST Momentary Footswitches (~15$)

-5 x chinese double relay modules (~ 15$) or better, DPDT version (much less noisy)

-12 x chassis 6.3 female jack (~20$)

-10 x leds (half of a different color)

-5 x 220 to 560 ohms resistor (peanuts...)

-some spare cable (...)

~70$ if you don't have any of these as spare

(not included: metal chassis or woodbox or whatever...)


and here are the tools:


-soldering station

-eventually some tools for wood/metal/plastic working


Here's the code part: (many thanks to Anton Efremoff for his feedback and suggestions) Tip: don't forget to add "//" on these two lines if you want to save your preset after booting it up!

//for (int =0;i<512;i++)
//EEPROM.write(i,0); It's here just for initialize EEPROM memory in case of debugging

You''l have first to download and install the keypad.h library here:

A big THANK YOU to Armando Colangelo aka 4Knobs Effects for this code . Note his project is based on a different approach that ommit the 3 positions switch and therefore adds 1 more selecting switch (6 instead of 5).

A video is available on youtube showing his awesome work.


check out some outstanding bands I play with

Cosmic Rain


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Please be positive and constructive.




hi CarraN, i am not sure to find the right instruction in this here.

I want to create a 4 way looper for 1 instrument,

it means , at one side 1 input jacket, at the other side 1 output jacket.

in the middle my arduino mega board with different switches, different LED, in the best way to serv the switches with my foot.

is your work suitable for me ?

kindly regards


i have problem with relay mode there is delay on switching. i need to double click the switch to engage the relay any solutions?

3 replies


are you sure you
have choose the right buttons? momentary ones or "Toggle button" instead
of on/off buttons... that means when you apply pressure, switch is "on"
and when depressed switch is always "off".


yes sir. another question do you experience loud popping on amps because of relays?

neither popping, nor delay, just some noise without booster and some distortion pedals...

I am starting this project soon. However, I have a question. Why do I need the VOltage regulator LM7805?

In this project it states buying one separately. I am looking at using an Arduino Mega and that seems to have one built in. Will I still need a separate one?

Also will the power supply power everything including the Relays or does the relay need a separate power supply. I am thinking of getting the dpdt relays as some people seem to have experienced noise issues with the cheap ones.



1 reply

Yes the regulator included in the Mega doesn't have enough power for the relays in my opinion but It's your to test it and your welcome to share if it does. And yes I confirm the relays I've choosen in this instructable had some noise issues. Take the ones Liwewire3 installed in his project. Cheers!


hi all did a quick write up on the looper build and use. may do an update later for now here it is. including schematic and code. cheers

1 reply

Hi CarraN, im seeing some issues with the relay module i have and wondering if anyone seeing same things. im using the 8 relay module intead of 4 two relay modules you use for my 4 channel looper but im seeing a strange voltage drop if all 4 loops 8 relays are ON. the regulator im using is capable of 5V 2A output. im thinking is the relays in this 8 relay module or all behave this way if you have them all on. how re you powering your 5 or 8 loop switcher and have you see any of this behaviour?


6 replies


how much current can handle your power transformer ? Try a 12v/3A
and maybe try another more powerfull regulator. Do you fix it a regulator radiator? You can fix your regulator to the metallic grounded chassis. By the way it seems an issue with power... See schematic again, it's all in there!


im using a l7805 2A to power the relay coils which is powered to a 9V 1A boss psa power suply. if i turn all 8 relays on and leave them on after a minute or so the relays go of as the voltage has droped to 3V from 5V regulator. im thinking that alot of power its been drawn to cause the voltage to drop. the connections are the same as you have but if you are not seeing any issues im thiking is these relays im using.

forget your boss power supply right now and go for a 9 or 12v, 3A ! Relays naturally eat a lot of power. And put your l7805 a eatsink or fix it to the chassis (if it's made of metal).

My relays take around 80mA at 5V when closed (and they're the bulky ones capable of hundreds of volts). 3A for 8 of them doesn't really sound right, unless the assembled relay boards are realyl that bad.

hi bananu7 that's more acceptable. i got these cheap from ebay to try them but not worth it. 80mA is still a lot but if it is no causing issues i would have gone with it. i think the 8 relay module i have is faulty and im going with DPDT relays. thanks for the msg

thanks for the reply CarraN. I wanted to know if anyone seen similar problems with these relay types. Throwing more power is not a solution for me. I'm powering my hole board with 5A supply and using 3A to power a switcher is not a good solution. These relay coils are expected to draw 35 mA each going by spec. So all 8 ON you would expect no more than 0.5 A current draw. Not that I believe the spec And you can't put more than 5V on them or the coil would go if they are speced at 5V. If no one here seen this issue I have a faulty relay module. thanks again for your help.

Hi CarraN, Ok, that is a good idea,So I have made a short image. Additional
I will mention, that always must be a connect through between input jack
and output jack.

Is your
solution suitable for me ?



Hi CarraN, thank you for your quickly response.

what i dont understand is, why do you use 5 pedals ?

For my 1 instrument ( = 1 input jacket ) , i should need 1 double relay, is'n it ?

I understand partially your sketch, but in the image, i cannot find out the relay connections of the relay and the mega board.

what can i do now ?



2 replies

5 pedals is the max that can manage Arduino uno. But if you want less -4 in your case- just ignore the fifth relay. That said you don't even need a mega for that purpose. So well, the input jack is connected on the pin 2 of the first relay board and the out jack is connected to the pin 5 of the last realy board like in the schematic. You don't need to cable the ground, just the live cable. The connections between the Uno and relay boards is as you wish, just pay attention to select the good digital pins in your sketch. Hope it'll help you.

Hi CarraN,
thank you for your patience with me. It is possible that we have a different wording and understanding of this issue ?
I am confused about the word “pedal” . In your schematic input jack is marked as “to pedal IN” , output jack as “to pedal OUT” .
What do you mean with this ? what is the function of your "pedal" ?

“to pedal IN” must be in my understanding “instrument IN” .
And “to pedal OUT” must be “to amplifier”
The only “pedal” I have are the foot switches to change the loop channel.
My plan is to have one input and one output jack.
Do I need for every couple of in/out jacks one relay
Or for every loop channel ?
What is correct ?
Sorry but I am musican, no specially technic freak.