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For my project, I have this power supply which makes me an unregulated 5V power input.

I'm willing to use it to power both my Pi and my 5V led strips. This power supply is rated at ±5%. I'm going to connect the +5V to the micro-usb +5V test point and GND to GND (to use the protections of the usb port). Do I need to insert any kind of regulator in-between? And if so, I suppose the 7805 family wouldn't be what I'm looking for as it needs at least a 2V drop. Is it?

Also, if I limit the number of leds to a max of 9A current use, would making all leds flash fast create any problem to the Pi's power input that a combo of a small and a big capacitors wouldn't "fix"?

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You should be able to power a Pi with the PSU output connected to the Pi's microUSB input (or equivalent points).

You will have to take off the supply for the LEDs before the Pi as there is no way 9 amps can be fed through the Pi.

As to whether the PSU can cope with powering the Pi and the LEDs - who knows? You will have to try.

  • Do you mean by "there is no way 9 amps can be fed through the Pi" that I can't use the same PSU for the leds and the Pi, or just that I can't plug the strips after the USB port (which is not what I planned to do, I was going to connect the led strips directly to the PSU pins)? – BriceP Oct 9 '16 at 10:09
  • I mean you have to connect the LEDs directly to the PSU, as you intend to do (but wasn't clear to me from your question). – joan Oct 9 '16 at 10:31
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If the PSU supplies 5V no regulator (other than a buck/boost switch mode, which are not normally used in this configuration) will work.

I don't know what the PSU is supposed to do, but if it supplies 5V±5% it should be OK.

Capacitors won't make much difference. The Pi (at least the current models) are not that sensitive to low voltage (although any peripherals may be).

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