user12108: I am looking for something like a multiway "relay dimmer".
Which lets me dim a light using an Arduino and a manual dimmer.

(The manual dimmer should work without any computer!)

user12102: You could use a rotary encoder for that purpose!
Basically the rotary encoder is a knob that, for every "tick" you give it, it returns a different value to your Arduino. With a bit of programming you can sense the direction of the turn, if it is positive then you lighten up the LED, and vice versa.
I used that to control a RGB led, it works very well! here some more information on the rotary encoder and the code needed to use it.

12108: <p>I am looking for something like a <strong>multiway "relay dimmer"</strong>.
Which lets me dim a light using an Arduino and a manual dimmer.
<a href="https://i.stack.imgur.com/d4pff.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/d4pff.png" alt="Schematic"></a></p>

<p>(The manual dimmer should work without any computer!)</p>
 12102: <p>You could use a rotary encoder for that purpose!</p>

<p>Basically the rotary encoder is a knob that, for every "tick" you give it, it returns a different value to your Arduino. With a bit of programming you can sense the direction of the turn, if it is positive then you lighten up the LED, and vice versa.</p>

<p>I used that to control a RGB led, it works very well! <a href="http://playground.arduino.cc/Main/RotaryEncoders" rel="nofollow">here</a> some more information on the rotary encoder and the code needed to use it.</p>
