Wich power supply ? How drive 12V with Raspberry?

Diy and Tweaks
#1

Hi !

i’m starting a volumio project with :
Raspberry pi (3b+ or 4 i have both and make testing)
This usb Dac
An oled screen : 2.42" OLED Display ssd1309 128x64
A momentary push button (12V white light circle)
Two vu meter here (12V needed)

i’m searching for a low level noise power supply for the raspberry and his Dac attached, and i need 12V for the vu meter and the power button.

wich power supply i needed ?
i would like use this product but i’m unable to find the good Toroidal transformer…

I have planned to power up the raspberry with the gpio (GPIO2-3),
how can i drive the 12V on with the raspberry power on ?

many thanks !!!

2 Likes
#2

So basically, you need a DC power supply that can provide +12V and +5V rails. From what I can see about the VU meter circuit, that draws around 200mA, which doesn’t make a lot of sense to me but that’s what the eBay description stated (200mA power supply requirement).

The Pi uses a power supply that I think is around 1A, to account for additional accessories and whatnot.

Your chosen OLED screen seems pretty economical on power (also requiring 12V, given the datasheet specifies an operational range of 7V to 16V).

Overall, I think the 12V power supply can be at least 500mA and your 5V supply could be about the same. That said, I’d just go with 1A for each rail anyway. You can always have a bit more current available.

In which case, the easiest approach would be to just find a 12V 2A (minimum) linear supply and hang a 5V 1A regulator circuit off the 12V output (think, 3-pin 7805 regulator IC with appropriate smoothing capacitors) with a heatsink, to be safe. The power supply you have linked to is overkill, given you’re running just an overall preamp section and no power amp. That said, it won’t be a bad thing either. Set it to 12V output and then add the 5V regulator circuit to the output of that for your two rails.

#3

Thanks metalio for your response !