Arduino control of Dimmer: Resistance Control?

Using Arduino Motors, Mechanics, Power and CNC
1

I can get these 10 Amp AC (Phase Control) dimmers (24-380VAC, 50-60 Hz) at a good price. They are controlled by a resistance / pot of 500K ohms of about 1/4 watt rating. They work fine with a typical resistance. NOTE: These terminals are "hot" at the line voltage, not isolated. At 0 output the line voltage appears across the resistance, as the resistance goes down the dimmer goes up and the applied voltage on the pot/rheostat (2 terminals) drops , all the way to zero at full brightness.

What is a good way to have arduino control these dimmers, without the complexity and cost of a motor-controlled pot?

LED to Photoresistor comes to mind. Anyone seen an off-the-shelf solution? DIY / epoxy would probably work.

Any other solutions I am missing?? Thanks!

OTHER: Anyone know how to "wrap" text around an image, or put the image on the right??

2

Glue a cheap servo to a pot shaft.
Cheap, simple, safe.

3

That's why I asked here! Thanks for one I didn't even think of...

I will try this with a 500K pot. The dimmer I tested here (at 220V) has first glow at 330K .

So maybe the servo rotation will be enough.. Depends some on the Servo, I think..

4

I had this idea using four relays and a sort of resistor ladder.

With judicious selection of the resistor values it will provide 16 discrete steps from full-on to full-off and nicely isolated from the Arduino.

DigPot.bmp (51.1 KB)

5

Digital Pot! THERE's an idea... There ARE "Digital Pot Chips"..
Anyone have experience with them?? Any that can handle 220volts??

Maybe several opto-triacs and resistors?? Like the MOC3061 (scroll down to it here: )
http://arduino-info.wikispaces.com/Popular-ICs

If the Solid State Dimmer Unit is $10 or so, the cost has to be pretty low...