Rob94hawk
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Does Raspberry Pi have enough power to control 50 LED's?

Wed Feb 06, 2019 7:38 pm

Looking to make a Christmas decoration using about 50 LED's. Will a Raspberry Pi be able to power them? Will be using different colors & want them to fade from low power to high power.

Here is the power requirement for 1 LED:

3.2-3.8V Forward Voltage, at 20mA current
Maximum continuous current: 30mA

Thanks

scotty101
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Re: Does Raspberry Pi have enough power to control 50 LED's?

Wed Feb 06, 2019 8:18 pm

No. You'll need a separate power supply

30x50mA = 1.5A.
A typical pi will require between 1.5 and 2.5A and most Pi PSUs will supply 2.5A. Not enough left to drive the LEDs.
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W. H. Heydt
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Re: Does Raspberry Pi have enough power to control 50 LED's?

Wed Feb 06, 2019 8:20 pm

30mA * 50 = 1500mA, or 1.5A. You're not going to get that from a Pi. The USB ports are limited to a maximum (combined) 1.2A. The GPIO pins can source on the order of 50mA *total*.

However, the Pi can *control* the LEDs just fine. Use a separate power supply to drive the LEDs and use GPIO pins to drive transistors as switches to turn them on and off in whatever way you want. It's like the difference between controlling the speed of a car by putting a very modest force on the gas pedal--which controls the engine speed by altering the throttle setting. The driver doesn't power the car, but he does control it.

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Imperf3kt
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Re: Does Raspberry Pi have enough power to control 50 LED's?

Wed Feb 06, 2019 8:39 pm

As others have said, you need a separate power supply.

But nobody yet mentioned that the Pi couldn't drive even one of those LEDs because they have a current rating of 20-30mA
The gpio can be used to power an LED but only if that led uses less than 16mA.


Go with the transistor (or similar method) way described above and don't be tempted to 'just try one' before finishing the system.
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Rob94hawk
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Re: Does Raspberry Pi have enough power to control 50 LED's?

Wed Feb 06, 2019 8:44 pm

So the Pi can control the changing and fading! Awesome! Thanks for the responses!

I've built plenty of pc's but I'm a noob when it comes to the Pi board.

Looking forward to this project.

mitsunataliya
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Joined: Thu Feb 07, 2019 6:25 am

Re: Does Raspberry Pi have enough power to control 50 LED's?

Thu Feb 07, 2019 6:33 am

No. Definitely you need a separate power supply, 30mA * 50 = 1500mA
USB ports are limited to 1.2A :)

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Last edited by mitsunataliya on Mon Feb 11, 2019 4:23 am, edited 3 times in total.

btidey
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Re: Does Raspberry Pi have enough power to control 50 LED's?

Thu Feb 07, 2019 9:20 am

With that number of LEDs you should check out using WS2812B pixel LEDs. A single GPIO pin can control a whole string as they are wired in series. Each LED can be independently faded and have its colour set as each one is RGB.

These LEDs are available as strips, circles, arrays or as individual dots. Although more expensive than raw LEDS they are still quite cheap and a lot more flexible.

If you have a higher power 5V supply (e.g. 5Amp) then that could be used to power both the LEDs and the Pi.

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