I've found a 5 V 3 A motor and I tested it using a lab power supply that limits the current draw to 3 A.
I've bought a 5 V, 3 A power supply without thinking that the motor would draw too much current if possible. In fact, it does draw too much current and the power supply goes into security mode about every 0.5 seconds.
How can I limit the current to 3A with a small circuit?
Here is the power supply I bought: https://www.velleman.eu/products/view/?id=433054
Here are 2 photos of the motor, I can't find the datasheet.
Btw, I assumed it's a 5V 3A motor: the lab power supply can only deliver currents up to 3A and I adjusted to voltage to 5V.
Best Answer
You bought the wrong power supply. No only does it have too low current output, but its over-current behavior is not what you want.
The supply should be able to handle the startup current, not the nominal running current. The startup current is probably considerably more than 3 A.
The supply should go into current limiting when the load tries to draw too much current. Yours shuts off for a second or two. That's not what you want.
The reason this works with your 3 A lab supply is because it is a current limiting type. At startup when the motor tries to draw more than 3 A, the supply's output voltage drops to where the motor only wants to draw 3 A. As the motor spins up, the 3 A point goes higher and higher in voltage. When it gets to 5 V (if it ever does), the supply then regulates the voltage to 5 V, and the current goes down as the motor speed increases further.