I have a fairly cheap breadboard power supply and a motor.

Now if I touch the wires from the adaptor (the thing that plugs into the power supply to provide it with electricity) the motor works fine and spins happily. I can adjust the voltage of this adapter to 3 volts - 12 volts, and the motor spins fine at all voltages. So I know the motor is working fine.

However if I plug the adaptor into the power supply and then try and power the motor from the power supply, it doesn't work. I try with both the 5 volt and 3 volt output of the supply. In fact the power supply appears to shut down - the led on it turns off.

What gives, why can this power supply not drive the motor? Is it just broken or is there some law of electricity I am not yet aware of (likely)?


Ok, so this is the motor I have : motor

And the power supply I have is something similar this : power

I can't find many details about the motor. But I have noticed for the power supply it says :

Maximum output current: <700 mA;

So I am guessing this is the problem? The motor likely needs more than that, especially if it needs 10x its requirement to get going.

  • 3
    \$\begingroup\$ If you have "a breadboard supply" and "a motor", all you can get is "an advice". To get any better answer, please provide details of your (a) motor; (b) "breadboard power supply" with schematics; and (c) details of your power adapter. \$\endgroup\$ – Ale..chenski May 18 '19 at 21:14
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    \$\begingroup\$ Most likely cause is the starting current of most motors is high - often 5-10x the rated current. Which will cause many power supplies to shut down before the motor's started. Does this apply to yours? No idea. \$\endgroup\$ – Brian Drummond May 18 '19 at 21:17
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    \$\begingroup\$ Interesting. Perhaps it is quite telling I don't really know what I am doing, I am just using cheap bits I bought on AliExpress. I'll see if I can find any details. \$\endgroup\$ – Mongus Pong May 18 '19 at 21:21
  • \$\begingroup\$ @BrianDrummond Supposing this was the problem, is the solution to get a better power supply? \$\endgroup\$ – Mongus Pong May 18 '19 at 21:22
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    \$\begingroup\$ Upvoting your question for confessing that "Perhaps it is quite telling I don't really know what I am doing", that's the proper attitude! LOL. There's probably lots of contact resistance somewhere, or a wire or something that was "cost optimized" in the cheap parts. \$\endgroup\$ – peufeu May 18 '19 at 21:41

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