Welcome • User Guide
ToS • Privacy • Canary
Donate • Bugs • License

©2025 Poal.co

787

I found this outlet plug deal at the dollar store for like ten bucks. I only bought it to open it up and have a look-see inside. Found this 110v AC to 5v DC circuit, as you'd expect. USB data lines don't run to anything (good!). The +5v lines aren't isolated from each other, so it's really just the one line shared by both ports. The wires hanging off went to the mains.

Would this be an okay circuit for a DIY Arduino project? Just needs to power the little AT board and a relay for switching on and off 110 to a heater coil periodically. Been wondering how I was going to do power supply for that project, and I like this little form factor. Probably end up removing the USB ports and just solder wire to the board.

I found this outlet plug deal at the dollar store for like ten bucks. I only bought it to open it up and have a look-see inside. Found this 110v AC to 5v DC circuit, as you'd expect. USB data lines don't run to anything (good!). The +5v lines aren't isolated from each other, so it's really just the one line shared by both ports. The wires hanging off went to the mains. Would this be an okay circuit for a DIY Arduino project? Just needs to power the little AT board and a relay for switching on and off 110 to a heater coil periodically. Been wondering how I was going to do power supply for that project, and I like this little form factor. Probably end up removing the USB ports and just solder wire to the board.

(post is archived)

You are currently inside a comment thread.
Click here to see all the comments (9).
[–] • 1 pt

Well, I don't really know enough to test for that. Do you have any pointers? What equipment do I need? Trying to learn here.

[–] • 1 pt

To test the current you'd need to put it on something where you could increase the load until it goes into shutdown.

Quality of the parts is hard to tell until it quits...

[–] • 1 pt

Alright... So basically I can try using it, and if it doesn't work then it doesn't work. Would there possibly be a failure mode that compromises my Arduino? It's not like they're expensive or anything, but I'd rather not ruin one if I can help it.

[–] • 1 pt (edited )

If the supply was designed decently, it will probably just shut down if you try to draw too much current from it. You could measure the DC voltage output as you apply it to the arduino, if it sags considerably or goes to 0VDC then you know you've overcurrented it.

Another thing you can check is for AC ripple on the power supply, measure across the output (under load) just like you'd measure DC. If you see a large amount of AC voltage (hundreds of mV) then it may not be suitable for use in a digital circuit. I've had some USB supplies that had enough noise on them they'd charge a device, but would make things act funny (touchscreens) while charging.

It shouldn't hurt your device. That's not a given, however.