Way to change potentiometer voltage via another circuit?

Thread Starter

Patrick Johnston

Joined Mar 2, 2019
4
I'd like to control the trigger on an xbox 360 controller (rotating potentiometer) using an exercise bike input. I figure that using an arduino I can produce a voltage signal proportional to the speed of the bike, and I'd like to be able to solder a few wires into the controller, and then make them control the voltage across the potentiometer to simulate a trigger press. I'd still like the original button to work when it's not in use. I'm not great with electronics, so I was hoping to get some ideas!

Here is my half-baked logic idea:

1) I can run a relay across the potentiometer with a resistor, and then use the arduino to open/close the relay with pulses, maybe with a capacitor or something across it to smooth it out? A lag of 1s would be fine.

2) Use the arduino PWM output to somehow inject/remove voltage across the pot. I'm not sure how this would work, given they have different power supplies.

Can anyone give me some advice what the best way to go is?
 

crutschow

Joined Mar 14, 2008
27,229
We first have to know what the pot does in the circuit.
You can't just arbitrarily inject a voltage at that point at expect it to do what you want.
 

dendad

Joined Feb 20, 2016
3,835
Why not have a servo actually turning the pot? That appeals to me.

I helped my granddaughter make an Arduino stop motion and time lapse controller for her camera. (It also had addressable LEDs around the camera lens for colour control).
I was going to open the camera and add a relay contact across the shutter release button but decided to put a servo on the outside to just push the button. One thing I was going to do but did not, was to replace the servo horn with a 3D printed finger just for fun.
A small servo is very easy to drive from the Arduino, and a rubber tube could push on to the pot knob so there is no need to open the controller.
 

Thread Starter

Patrick Johnston

Joined Mar 2, 2019
4
If I wanted to remove the pot altogether, would there be any issues if I just fed the smoothed arduino D/A converter output straight into Vx, and remove the pot?
 

dendad

Joined Feb 20, 2016
3,835
If I wanted to remove the pot altogether, would there be any issues if I just fed the smoothed arduino D/A converter output straight into Vx, and remove the pot?
It looks like you need to scale the Arduino smoothed PWM analog out to range from 0 to 1.6V. That is not a hard thing to do. A resistive divider would probably work ok.
 
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