I am trying to run a pro mini off of 6 volts. I am also trying to run a servo with the same 6 volt external supply. The servo misbehaves. If I take a 9 volt battery and connect it to the board and also to a regulator knocking it down to 6 volts ( connected to run the servo) everything works. I would like to run the board and the servo on 6 volts. Is that possible some how? Thank you. also if I connect the 9 volts to the board and use the built in regulator on the board (5 volts) the servo is erratic.
How are you connecting the 6V supply to the Pro mini ?
Which pin on the Pro Mini are you connecting the positive of the 6V battery to? 6V is too low to connect to the VIN/RAW pin, you should supply it with at least 7V.
7V is the minimum to run the Pro Mini. I can't be sure how the servo will work with that, or what the minimum input voltage is for the regulator you use for the servo.
Moved your topic to it's current location as it is more suitable.
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The Promini regulator is only good for 150mA of current. That is typically not enough to power a servo.
At the same time, the regulator needs more than 6V to put out a regulated 5V for the processor.
Sounds like you fried the 5V regulator some where along the line so the processor was not powered.