12V LED Dimmer that reads 110V Value from Dimmer...

Projects General Guidance
1

So, what I am looking to make is a dimmer for LED strip lights that can be have the level controlled by a standard Triac based 110V household dimmer (which, in this case would be a Insteon dimmer).

The problem I've encountered with many off the shelf dimmable controllers is that they don't work well at low light levels. I'd like to solve this problem by having the controller powered on all the time and only use the dimmer circuit to detect the desired dim level.

I've got the LED dimmer part working with triac based PWM dimming, but what I need is to be able to read the desired level from the 110V wall dimmer. It seems that any and all searches for dimmer turn up only the ability to MAKE the dimmer, when what I need is the ability to read an existing commercial dimmer.

Thoughts?

2

A transformer should work. And, a transformer will isolate your low-voltage from the high-voltage, which you need to do for safety.

You can make an unregulated power supply from a step-down transformer, a full-wave rectifier, and a capacitor ([u]schematic[/u]) .

If your LEDs run directly off 12V, that should work as-is.

A few things to be aware of:

  • Transformers are generally rated at their maximum current. At no-load or low-load, a 12V transformer will typically put-out more than 12V.

  • There is approximately 1.4V dropped across a full-wave rectifier.

  • An AC waveform has a peak voltage 1.4 times the RMS voltage, and the capacitor will charge-up to the peak.

So if you use a 12V transformer, you may need to add a current-limiting resistor