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Topic: Dimming an LED strip (Read 5 times) previous topic - next topic

chaser53

I have an RGB LED strip from Radio Shack and I am making a visualizer. I am new to circuit building (not programming) and am trying to figure out how to dim the LED strip with one of the digital or analog pins. The only issue is that the strip requires 12vDC to run properly and if I recall correctly, the max for any one of the pins is 5vDC. I have looked at JFETs, Digital POTs, or making a jerry-rigged one by combining a flat led with a photo-resistor. My question is: How can I control a 12v current (I would like to be able to control the output voltage from between 0-12 volts) using a 5v pwm signal.

Thanks

Hippynerd

http://learn.adafruit.com/rgb-led-strips/usage

That will give you an idea, exactly how you do it will depend on the LED strip. My guess is that your LEDs will require a separate 12v power supply and some transistors of some sort at the very least.

Magician

How long is your strip? 5m would require transistor, less than 1m you can do with ULN2003/ULN2803

arduinohabib

Yeah you can drive it with a transistor or mosfet. I recommend the IRF540N mosfet.
What is man's best friend? The breadboard!

chaser53

The Transistor seems like a good idea. The 1 meter strip I have has the capability of lighting up individual lights instead of the whole strip being one color. It uses a TM1803 chip to control the led colors. The only problem is that if power is disconnected, the whole strip resets. Is there a way to maintain a constant power to the strip using a transistor connected to PWM?

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