Arduino/stepper/servos/switch - please advice if circuit is correct.

Hello Friends, I am using a 12V 1.5A power source to operate a stepper, bump switch, and two servos based on the circuit design below. I have managed to get the stepper working correctly with the switch. However I am not sure if the servos are connected correctly or if any addition components are required e.g. transistors, capacitors, resistors, etc. I would greatly appreciate any feedback.


Looks good to me.

You need some capacitors on each side of the voltage regulator. A 0.1uF ceramic and a 10uF in parallel on each side should do.

Can you please elaborate a bit on what the capacitors would do for the circuit. Thanks!

The power supply I have is 1.5A. The stepper is 0.33A. The two servos are approximately 10mA idle, 500mA no load operating. Is the 1.5A power supply enough or should I get a higher amperage adapter?

A while back another user had directed me to this drawing below, however it seemed to have a few more things going on in it that I did not understand. But I see a capacitor in there also.


1.5 amps might not be enough for the servos and motor if they all start up or change direction at the same time or if there are any significant loads involved. You will most likely be ok, but if it behaves unpredicatably or the Arduino resets, you need more amps.

See the links in my signature for some servos pulling 1+ amps under load

Duane B

Can you please elaborate a bit on what the capacitors would do for the circuit.

It would stop the regulator from oscillating and working incorrectly.

You need them, see the data sheet for the regulator you are using if you want to know the minimum value.