DC Motor pulsing

I have a 12v DC Motor connected to a 18.5v 3A Laptop power supply. When I connected the setup the motor is working but it is pulsing(Working with regular intervals of idleness). The problem is getting the motor to rotate continuously without pulses. If I shorted the connection for some time, It will work perfectly after that with no flaws. I’ve also tried a 40V Printer power supply(I don’t know the Amps). I tried connecting 4400μF capacitor(Rated for 50V) in parallel to the Motor but It didn’t show any change at all!

What am I doing wrong here? Any resources for further reference is very helpful.
Thank You :slight_smile:

Have you tried running the 12V motor with 12V?

What setup?

Maybe because the 12V motor is cutting off at some portion of being driven by +18V?

More that likely the power supplies are being overloaded because you are just guessing at the current your motor is drawing.


More that likely the power supplies are being overloaded


The motor startup/stall current is typically 5-10 times the no load, free running current.

Most power supplies cut out on overload, whereas for a motor you want current-limiting behaviour
on overload, since the initial stall current is likely to cause overload-cutoff-recovery-overload-cutoff…

Either you need a supply that current-limits (without foldback) or use a supply with enough current for
the stall current of the motor.

The amount of capacitance needed to tide a motor over during stall current conditions is prohibitively
large (and would cause the supply to cutoff itself anyway)