Powering my mirror?

MadScientist

You should check how much power your mirror, incl. screen and RaPi, consumes and buy an appropriate LED power supply. Especially the IP67 ones are very slim. My 60W power supply is only 33mm high. My whole system uses max. 30W so I decided to go bigger (46W was out of stock, 50W has the same dimensions). If you’re at max. below 30W you could aim for a 36W power supply that are even smaller (I think 20mm high).

You could use buck-boost-converters to adjust the voltage you need for the Pi or the LCD. In my case the LCD is driven by a V59 universal controller board that runs on 12V, so it can be powered directly from the supply. The Pi will get the power also from the power supply but with a buck-converter in-between, that reduces the 12V to 5V.

The Bean

I’m actually not sure what to check for watt consumption. I’m only seeing volt and amp.

MadScientist

You could use something like this:
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You plug in the wall outlet and then you plug the power supply into this device. It will show you voltage, amperage, wattage, etc. They are very cheap. I think I paid for mine around 5€ 5 years ago.

Or, if you know how much ampere is used at a known voltage, you can easily calculate the wattage by multiplying amere A with voltage V, e.g. 3A at 12V would result in 36W.

The Bean

@MadScientist ok so you example is exactly the specs for my display. And from what I’ve seen RasPi3’s won’t reach 4 watts. So any psu over 40 should work, correct?

MadScientist

@The-Bean
They say the power supply should be able to do 20-30% more than what you need. So better aim for 45W. Something like this should do. Just check Amazon or eBay in your local country. They are usually very cheap and do the job just fine. I use 2 of those (30W) to drive LEDs for years now.

cruunnerr

@The-Bean said in Powering my mirror?:

I’m actually not sure what to check for watt consumption. I’m only seeing volt and amp.

W = V * A (Watt = Volts * Ampere)

doubleT

I put a hole in the drywall and made a neat little sunk in box with outlets for power (with a PIR for the monitor) and usb (for the pi 24/7) – no visible cables – but I know sometimes that’s not possible.

My plan b was a cable that I’d sleeve really nice so it doesn’t look too bad that goes to small cable box where the cable is split and connected with a plug for the monitor (or in your case the psu) and a converter with a usb plug. Just be careful when working with electricity. I learned a painful lesson on that when I built my Mirror.

The Bean

@MadScientist probably an ignorant question. But will that still work if split between the step down to a 5v, as well as the 12v controller board?

MadScientist

@The-Bean
In my case the RaPi takes less than 0.4A with very short peaks just above that. So the consumption is around 2-2.5W incl. keyboard and mouse. Add this to your screen consumption and add 20-30% on top of that. So 45W is the minimum, 50W and above should be the better choice. But it also depends how long the screen will be on. If it’s just for a couple of minutes every hour or so, 45W will do.

The 12V/3A of your screen, are they measured values, or are they from your manual? What screen are you using?

The Bean

@MadScientist it is the recommended power for the controller board https://rover.ebay.com/rover/0/e11400.m1842.l5919/7?euid=5138ba89bae64ecd98354e79c15592eb&bu=44095069551&loc=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fvod%3Ftransid%3D1755030964001%26itemid%3D112175476566%26qu%3D2&sojTags=bu=bu
It’s an old laptop screen.