I have a tiny DC motor directly connected to this power supply. The motor starts just fine when the supply is set to 4.5V. I can then change the voltage to 6V and it continues to run just fine. However, if I try to start the motor at 6V it only runs in pulses (for about 100 milliseconds once every second). Also, if the motor is running at 6V and I apply significant load, it begins pulsing until I lower the voltage. I'm guessing both cases are explained by the larger current required to start the motor at a higher voltage, and to keep it running under load.
I have a few questions:
- What is actually happening to cause the pulses? Is my power supply overloading then "resetting" once every second?
- Is there something very simple I can add into the circuit to allow it to start at higher voltages (a momentary current spike)?
- Is there something very simple I can add into the circuit, perhaps a better power supply, to allow it to run under sustained load (a constant current increase)?
Best Answer
I'll turn our comments into an answer.
It's likely that the motor is tripping the current protection circuitry on the power supply when it's starting up. Then the power supply resets and all starts again generating the pulsing effect.
In his comments, WhatRoughBeast suggests you get a bigger power supply.
I've expecienced that once and what I did to work around it was to replace the wall-wart by an equivalent set of AA bateries. They usually let you draw a few amps at start up without any limiting circuitry to get in the way. In your case, 4 AAs in an appropriate battery holder will do the trick.