Have you seen this switch?

Question

I'm going to do my best to describe the switch I'm looking for.

I'm looking for a knob or dial that acts like two momentary pushbuttons. Throws one momentary push button when you spin it clockwise every degrees and throws the other when you spin it counter-clockwise every degrees. The knob should have no stops.

The application is to interface with a micro and a digipot for volum control of a homemade preamplifier. Imagine an AV receiver (without motorized pot) you've seen and how you can adjust the volume with the kno on the front or a remote control. This is for that knob on the front.

Didn't think it would be hard to find but perhaps I just don't know wha to search for! What's this thing I'm describing called and where can get one?

Dave · Accepted Answer

Smmething like this?

larwe · Answer

These applications do not (as far as I have EVER seen) use a switch of the type you describe. They use a quadrature encoder, either mechanical or optical. The encoder is a three-pin device; one common, two outputs. Typically you'd wire the two outputs to pins of a micro, with pullups, and the common pin goes to ground. As you spin the knob, the two outputs produce a square wave 90 degrees out of phase. If A is

90 degrees ahead of B, you're spinning in one direction; if A is 90 degrees behind B, you're spinning in the other direction.

It's not the right shape for your application, but a switch I have used that you can view as a reference for the general part family is Panasonic's EVQ-WK. (This is a thumbwheel type switch with clicker function, as used on camcorders etc).

donald · Answer

Joel · Answer

pushbuttons.XThat sounds great.  I've got some more words to search with.  Thank you.

Joel · Answer

Just what I need -- detented even for that incremental volume feel.Should turn out very nicely.  Thank you for the lead!

Have you seen this switch?

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