Saturday, August 6, 2011

Motorized Potentiometer

I had a broken micro RC car that used a gearbox with a tiny potentiometer on it for controlling the steering angle. I thought it would be interesting to replace the little potentiometer with a regular sized version so I could set the position either manually or from a microcontroller by driving the motor.

I drilled a bit of brass rod to fit over the gearbox output and to fit the stub of shaft on the back of the pot. I used some loctite and epoxy to connect the shafts together, and ran it a bit to get it all concentric, then epoxied a bit of aluminum strap to both.


The next step is to come up with some code to read the pot and drive the motor to the commanded position. Since it holds position without power to the motor, the h-bridge can be left idle except when it is moving to a commanded position, so that a user can turn the knob to adjust a setting.

4 comments:

Kevin Fusselman said...

I think I'm missing the point... Aside from some stereo gear that uses a control like this as a novelty, what's the application?

Dave said...

'Most Useless Knob' machine? Resets itself to zero every time you turn it?

I actually didn't have anything in mind, I was just poking through the parts bin and found some things that looked like the could be stuck together.

Dave said...

You know, I was joking about making a 'Most Useless Knob', but now I think I'm going to have to that.

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