Can you overpower an Arduino?


Quick one for you Arduino guys… before I smoke a board :fire:

I have an ESP8266 controller that I want to power with / and control an ATX power supply. Turns out the ESP board only has a 3.3v power pin (but allows USB power through the USB plug presumably at 5v) and the ATX hot bus is 5v.

Will powering the ESP board with the ATX 5v smoke the board? If yes, can I just add a resistor on the line and drop the 5V down to 3.3? If it’s then at 3.3, will there be enough power to switch the ATX main bus on as well as power 4 relays that will drive the 12v ATX leads?


Yes it will you need to drop the voltage down.


If you can find a way to attach the 5V from the ATX power supply to the USB 5V rail, you’ll be good. See if there’s a header labelled 5V on the ESP controller. The ESP controller you have likely has a power regulator to drop the supplied 5V from the USB to 3.3V for the ESP.

As for regulating 5V to 3.3V yourself, you won’t do that with a resistor. Take a trip through the interwebs and look up “Low Drop Out regulator” or “LDO regulator” or “LM317”. Probably the best thing for the job and pretty straight forward for folks just starting out.

From imperical evidence, probably not immediately, as I’ve done this by accident and didn’t discover the oversight for quite a while. But, you will be running it out of spec and it will fail eventually. In my case, it seemed to be functioning, but certain aspects of the ESP didn’t work right. It never recovered. I had to fix my power issue and replace the ESP to get things stable again.