I have a project that has 2 12V .2 amp fans, and 1 30 3 amp LED COB panel, and a 5 V Arduino. I was wondering if there was a simple method to power all of these devices from a 120 V wall outlet?

As of right now considering a 30 volt AC to DC power supply. Then a series of switch buck converters. Or something along these lines.

Thanks for the help.(also I realize there was a similar post before but wanted some additional insight)

  • 1
    what is a 1 30 3 amp LED COB panel?
    – jsotola
    Commented Apr 16, 2023 at 20:33
  • Assume "1 30 3 amp" is actually "1 30 volt 3 amp". You can do what you said. You can use 3 independent power supplies ... as long as you connect the grounds together (nitty gritty: As long as they are either all floating or the negative lead is ground). But, wow, 30 volt 3 amp LED??? You sure that's a voltage regulated power supply? Or is that a current regulated power supply? If the latter ... well, that puts into question all our assumptions and solutions.
    – st2000
    Commented Apr 16, 2023 at 20:41
  • This is better asked on Electronics Stack Exchange
    – Nick Gammon
    Commented Apr 19, 2023 at 7:26

1 Answer 1


If it wasn't for the LED panel then I'd say use a mains to 12V DC power supply. You can then get small off the shelf switching regulator modules that with the addition of a couple of capacitors will reduce that down to 5V for the arduino.

If you genuinely need 3A at 30V (90 Watts of LEDs? That's a LOT of light) then use a compatible mains supply for that. You can get off the shelf switching modules that will drop from ~30V down to 12V 1A, they are a little more expensive than 12V to 5V parts, mainly because it's a less common requirement, but a quick search on RS shows up some options for around $15.

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