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I searched the forum but didn't get a clear answer.

I have a "LED tinsel" powered by an USB plug. I tried connecting a 5V pin of my RasPi3 GPIO to the "+" pin of the USB plug, and a ground GPIO pin to the "-". It works. I tried connecting a 3.3V pin to the "+" (and ground to "-"). It works. But trying to power the tinsel by connecting a GPIO pin set to "OUT" to the "+" and a ground pin to the "-" doesn't works.

What am I missing ?

You can guess that I would like to activate/deactivate power of the tinsel from programming.

Thanks !

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  • The GPIO pins can only provide a few mA which is not enough to power a device. You need a switchable component like a relay.
    – Robert
    Commented Dec 9, 2020 at 19:52
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    The GPIOs are intended for signalling. "I would like to activate/deactivate power of the tinsel from programming" -> You can toggle a transistor on the 5V using a GPIO. You will need to find out exactly what the current requirements of the tinsel are.
    – goldilocks
    Commented Dec 9, 2020 at 20:15

3 Answers 3

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When the GPIO pin is set to OUT mode, it can be in two states, LOW or HIGH. Have you put your pin into HIGH state? If yes, then it's possible that the GPIO doesn't provide enough current to power a LED tinsel.

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What you are missing is a specification: "How much current does your LED Tinsel require to operate?" Give us that info, and we can give you a definitive answer - without it, we have to guess - and that's a waste of everybody's time, no?

I Guess:

The GPIO pin can not supply enough power to drive your LED Tinsel. You can do some research on that. You might start by reading this Q&A.

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The solution was to set the OUT mode to HIGH !

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    Beware that there is no "safety" (unless you add an appropriate resistor) -- if the tinsel draws too much current at some point, it can permanently damage the pi.
    – goldilocks
    Commented Dec 11, 2020 at 18:47

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