So I have an Arduino Nano powered in parallel with an ESP-01 (for the ESP there is an extra LM1117-5.0 voltage regulator in series).

+12V ---------+---------+
              |         |
             Reg        |
              |        NANO
             ESP        |
              |         |
 GND ---------+---------+

My problem is that after a while, the Nano burns (my guess is the difference in current that both devices draw).

In any case, what could be the reason and what could I do to fix it?


  • how are you connecting the 12 V supply to the nano?
    – jsotola
    Oct 3, 2019 at 4:09
  • I´m using the Vin pin.
    – Jose Tomas
    Oct 3, 2019 at 4:17
  • "for the ESP there is an extra LM1117-5.0 voltage regulator in series" ... shouldn't an ESP-01 get 3.3V?
    – gone
    Oct 3, 2019 at 6:47
  • 1
    please do not crosspost ... electronics.stackexchange.com/questions/461286/…
    – jsotola
    Oct 3, 2019 at 8:09
  • Didn't know, deleted the duplicate one. Thanks.
    – Jose Tomas
    Oct 3, 2019 at 15:19

2 Answers 2


Use the 5v regulator to power both the ESP and the Nano. Those onboard regulators have minimal heat dissipation and if they burn out you lose the whole Nano. Check how hot your external regulator gets and mount it on a heat sink if it gets too hot to touch. NB Connect the regulator output to the Nano 5v pin directly


12V is the upper limit for input voltage on an Arduino. With a 12V input the regulator has to convert 12-5, or 7 volts, to heat. (That's how linear voltage regulators work.) As the other poster said, Arduinos don't have much heat dissipation on their voltage regulators.

Like jksemple, I would suggest powering both the ESP and the Nano from the external regulator (You might want to cut a USB cable and wire it to your external voltage regulator, then plug it into your Nano. That way you're not bypassing the power control circuits on the Nano.

By the way, did you build a full voltage regulator with the LM1117 chip? You need some extra components like capacitors and resistors to complete the voltage regulator.

Finally, you might think about using a DC-DC buck converter rather than a linear regulator. That will run a lot cooler and waste a lot less power.

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