How do I create a knob like on my amplifier

Question

On my amp, I have a big round knob, that I can turn forever in both directions, to control volume. It simply turns up whenever I turn clockwise and down when I turn counter clockwise. There is no limit as to how far I can keep turning it.

How do I create this in my own project? I have an arduino where I want a knob like this, to control a value in the arduino memory. Simply, turning up, add to value, turning down, subtract from value.

I assume I need some kind of potentiometer, but they do not turn forever, do they?

Actually there are potentiometers, usually with two wipers, that do turn forever. However, those are not approriate for what you are asking about. — Olin Lathrop, Jan 04 '14 at 16:37

score 10 · Accepted Answer · edited Jan 04 '14 at 18:51

10

What you need in a rotary encoder, they have two outputs that generate pulses which are then decoded to read the direction of rotation.

Rotary mechanical encoder Rotary mechanical encoder waveform

Refer to http://playground.arduino.cc/Main/RotaryEncoders

To control the volume you can use Arduino to drive a volume control chip like PGA2311.
There are even 4 channel versions like PGA4311

You can also control digital potentiometers like MCP41xxx/42xxx

edited Jan 04 '14 at 18:51

Diego C Nascimento

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answered Jan 04 '14 at 15:31

alexan_e

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@DiegoCNascimento I suggest not to link Arduino directly with the answer The OP asked specifically for Arduino so why including an Arduino link with a library for his needs is wrong? – alexan_e Jan 04 '14 at 19:17
ops, have not read that, sorry :) – Diego C Nascimento Jan 05 '14 at 00:12

How do I create a knob like on my amplifier

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