I'm trying to understand how to control an RGB LED strip, I set up all the TIP120 (because I could get my hands on an n-channel mosfet), if I power everything in this way I can change colours and everything: enter image description here

but now I'm facing a dilemma now, whats the correct way to manage to switch my power strip ON/OFF based on an input from a pir sensor? I mean, how can I handle 12V 3A (requested by my led strip), how do I correctly wire my Arduino up in order to make it switch the LED strip ON/OFF?

1 Answer 1


That's pretty simple: when you turn off all the colours you are actually turning off the entire strip with very minimum leakage current in each of the three FETs.

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    Oh...really? Is that so simple? Do I need to use some king of Voltage regulator? Is it safe for my Arduino to receive a 12V in(yes) at 3A(I don't know)? The schema provided so will be ok? I don't even need to put 12V into my Arduino..right?
    – FabioEnne
    Sep 26, 2016 at 8:23
  • @FabioEnne With the schematic you have provided the 12V doesn't go anywhere near the Arduino.
    – Majenko
    Sep 26, 2016 at 10:22
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    @FabioEnne The FETs (or TIP-120s if you must) are just switches. Just like a light switch. Only for dimming you switch the light switch on and off really really fast.
    – Majenko
    Sep 26, 2016 at 10:29
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    That is correct. 0 is off. All three channels at 0 the entire strip is off.
    – Majenko
    Sep 26, 2016 at 10:42
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    @FabioEnne You only need a voltage regulator when you want to change a voltage from a higher one to a lower one for the purposes of powering a device.
    – Majenko
    Sep 26, 2016 at 14:33

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