Rotary encoder detent pulse to simple DC pulse circuit. Arduino?

I have spent the last 10 years restomodding a classic car. In the space where the 8-track player was I’ve installed a P88rs Pioneer head unit with a plug at the back for steering wheel controls. I have an Aerpro universal steering wheel adapter and know the Pioneer resistor values I need to use to get my headunit to do Volume up and Volume down and also Source/mode.

I have my eye on a rotary encoder with detents (i.e. it pulses) and a momentary push switch on the shaft. I’m not sure if it’s the one I need.


I don’t have any buttons on my steering wheel but I do have a spare knob on the dash - the old “Radio Balance” knob - where I could put the rotary encoder and plenty of space behind the dash for a small decoder.

I need to know what I need to buy (and do!!, especially do!!) to send three simple electric pulses to the steering wheel adapter when the knob is turned.

It’s a 5 volt circuit and the 3 output wires of the circuit will have the appropriate resistors on them to do the Vol+ , Vol- , and Source.

I have an arduino Uno R3, a breadboard and solder less wires in my basket. What should be my next step? I’ve been reading Arduino forums and talking to various electronics suppliers but I’m still very confused.

It can’t be all that complicated surely? It’s a simple conversion of digital information to electric pulse.

Any help or advice anyone can give me will be much appreciated. There are a lot of people over the years where this idea has been floated but I’ve never seen a successful conclusion.

Cheers - and hi as a new user ( and new to this sort of electronics) - Jeff

He Jeff

We have a tutorial on how to use a rotary encoder and there is an Arduino Playground tutorial that goes more in depth.

I think the best way would be to use the Arduino to detect the encoder and then the digital out pins on the Arduino are 5V so they should just connect directly to your resistors and head unit.

Thanks for that Clinton, I have been trying to figure this out on my own for months.

I also have question regarding one of your rotary encoders ( Rotary Encoder + Extras SKU: ADA377) ; is the push button on the shaft momentary or push on/pull off?

Also, because the whole box and dice is being squeezed behind the dash what is the smallest Arduino board I could use?

Hey Jeff,

That one is a momentary push. You could use the Arduino Nano or if you could use the Mini though it does not have the USB interface so programing is a little more difficult to set-up.

Once again thanks - I’ll go with the nano; it’s an easy enough matter to solder the 5V +ve to the vin pin. The momentary switch is the one I’m after as well. I’ll order everything next payday and dedicate a few days to learning the basics. I’ve got plenty of LEDS and a multimeter to test if the output is what I’m looking for.

I’ve also found a simple diagram to get me started with the wiring.