SparkFun Forums

[Wolframium]

I recently got some 12V 5050SMD RGB LED strips, and as interesting as they are, all the current controllers I can find for them are quite boring. I am trying to design my own which can do all the things I want it to, such as change color and power based on the current time and temperature, among other things. The actual sensor and microcontroller side of things should be reasonably simple (I'm just going to go with a parallax propeller because I've used one before), but the one thing I cannot figure out is how to properly drive the LEDs themselves.

The actual operation of the LED strips is quite simple, there is a common +12V and a ground for R, G, and B. I have a quite powerful 12V power supply already, and the propeller should generate a nice 3.3V PWM signal for each channel, but I can't find any good chips or circuits to turn the low power 3.3V PWM signal into a 12V @ ~15A PWM signal. Any help with the best way to do this would be greatly appreciated.

[colin55]

All the strips will have current limiting resistors.
You just need to drive them with a transistor for each colour

[Ross Robotics]

Like colin said, you will need transistors that will turn on and off the LEDs with a 3.3V signal. But one transistor may not be enough to drive one channel. You may need to use several to get what you need. But transistors probably won't be fast enough to get the PWM frequency you want.

That would be alot of components though. You need to find a PWM driver that has low logic voltage.

[Mee_n_Mac]

The actual operation of the LED strips is quite simple, there is a common +12V and a ground for R, G, and B. I have a quite powerful 12V power supply already, and the propeller should generate a nice 3.3V PWM signal for each channel, but I can't find any good chips or circuits to turn the low power 3.3V PWM signal into a 12V @ ~15A PWM signal. Any help with the best way to do this would be greatly appreciated.

So each LED is not individually controllable ? All the R LEDs are basically in some series/parallel combo w/dropping resistors inline. What you want is a high current MOSFET, controlled by 3.3v. IIRC we had another thread with a similar need. Alas my 3 remaining neurons can't recall the topic.