Pro mini driving servos???

All my servos work when my Pro Mini is powered by the computer power input. However when I use the raw input with 9V, single or ganged, batteries, the small servos still work well - but the hi torque servo does not - it seems to reset continuously. Why does the latter work with the computer power input but not with the "raw" 9V input?

Your servos require +5vdc to operate. The amount of +5vdc current required depends on how many servos, the amount of mechanical load on them and the specific model of servos used. In your case the servos are able to operate from the current limit allowed from the USB power source, but marginal if using the on-board +5vdc voltage regulator.

Most serious servo applications would utilize an external +5vdc power supply (or higher current capacity batteries, not small 9v battery) that would be able to handle the servos current demands. Powering servos from the boards +5vdc pin is all often a problem.


Many thanks Lefty

For using servos with arduino you really want to always power then from an external supply and just have the signal pin to the arduino. Saves the onboard regulator and protects the arduino.