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Topic: 12v RGB LED Strip???? (Read 1 time) previous topic - next topic

Moloko

does anybody know?... I am trying to use an Arduino to control an RGB LED strip that has a common cathode and an anode for each color. I am using a TIP 120 and 2.2K resistors to get my current and voltage right, just can't seem to figure out how to get 3 PWM Arduino pins working for the colors. Any advice?

RuggedCircuits

If you have a common cathode display then you should probably use a PNP transistor (or P-type MOSFET) to drive each color rather than a TIP120.

Here's an example for driving a 12V solenoid -- you can use the same circuit and eliminate the diode D1 since the RGB LED's are not an inductive load.

http://ruggedcircuits.com/html/circuit__19.html

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, speaker, microphone, light sensor, potentiometer, pushbuttons

Moloko

thank you sooo much!!! I'll see whats up and post again after I try it.

Moloko

ok... from the circuit I see that I can use a P2N2222A for T1. But I might not have a TIP 137 for T2. Is there any substitutes that will work?

RuggedCircuits

Any general-purpose PNP transistor that can handle your RGB LED strip current (what is it?) should work.

Some other common part numbers that might work are 2N4402, 2N4403, BC327, PN2907, MPSA55, MPSA56. But really, there are a LOT of PNP transistors out there.

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