# Help with powering magic mirror

Hey guys! I’ve previously asked a similar question on this forum, but have gotten much closer now to completing the project and have since added a few things, so just wanted to clarify.

I’m making a magic mirror/smart mirror for my partner, and am having an issue with the fact that it’s going to possibly have 3 power cords coming from the back: Monitor, Pi and RGB strip.

I’d like to make that one, but am not quite sure on how to do it. The monitors standard power supply is 19v 1.5A, could I get away with purchasing a 19v 6+A power supply, mounting the brick in the back of the mirror, and having it supply the monitor and a 5V voltage regulator such as this:

Which could power the Pi and the RGB strip? Would I just power the monitor and the regulator in parallel from the power supply?

Is there anything else I’d need, other than some wires, solder, the regulator and the power supply?

Edit: I should mention the RGB strip runs around the outside of the backing of the frame, you can see the wires poking in through the top left of the picture of the back of the mirror. Also, the tape is just to block the light around the ugly cutout I made for the monitor, the wooden brace is screwed in from the sides and there is another one to go at other end of the monitor.

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Hey Chris,

Awesome project! and very sorry for the delay.

To power your project the first port of call would be to figure out the total power being input.
The Monitor will be using around 30 Watts ( = 19V * 1.5A), the Pi will be using around 16W (= 5.1V * 3A for the Pi 4) and the strip will be dependent on the strip that you use. an addressable strip will use around 5V at around 2.1A at full brightness per meter(let’s use 2m in this example, so 22W)

All up that will be 70 Watts of power, accounting for efficiency losses in the regulator an 80 Watt supply should work. Meaning around 19V @ 4A.

That regulator would be perfect, although switching the LED’s on and off may introduce noise into the supply, but should work.

Off the top of my head, it sounds like you have covered all of the bases, with the wire, solder, and regulator.

Let me know if you have any other questions and I can give a hand!

Cheers,
Liam.

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Thanks Liam! I’ve just ordered the reg and a 90W power supply so will no doubt have some more questions in the next few days.

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Hey all, does anyone know which cable is positive and which is negative on the genuine Pi charger? One has black stripes, the other has text (AWM 2468 18AWG VW-1 80oC 300V E77981 WONDERFUL-D)

ok put a dmm on it …check polarity if unsure

Thanks all for the help so far! She’s all powered up and running. I’m just trying to get the software side of the RGB’s working. I’m worried the NeoPixels could draw too much power (they definitely have the potential to if they’re all on max white) but I’ll try to find a way to make it max at ~50% brightness as they’re only there to give the mirror a “glow” effect, not to light up the room. I might also make them dance to music but we’ll see about that later.

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