I have a problem with a power supply ,which is 12v 2a.When I plug in a motor,the motor starts and then stops and then again starts and then stops.When I measured the voltage is 12v,but when I measured the amps they changing! Can someone tell me what might be the problem? Before it worked without problems with the same motor,but now starts and interrupt and then again.The motor working,because when I pluged it to another supply with the same specs works good!

 

It might be as simple as the motor's current requirements (particularly the stall current) is too close to the power supply's current limit threshold. Foldback current limit could easily give the effect you reported if the timing is right.

 

It might be as simple as the motor's current requirements (particularly the stall current) is too close to the power supply's current limit threshold. Foldback current limit could easily give the effect you reported if the timing is right.

The charger worked before with the same motor without problems!

 

The charger worked before with the same motor without problems!

Likely the supply is marginally at it's limit when starting the motor as DC stated.
What is the motor load?

 

The charger worked before with the same motor without problems!

Likely the supply is marginally at it's limit when starting the motor as DC stated.
What is the motor load?

Likely the supply is marginally at it's limit when starting the motor as DC stated.
What is the motor load?

It's 370 motor,I required 12v 1.4a
There is no load.

 

A motor can require 10 times its normal running current to start.
You may have to limit the current for starting.
One way is to have a small value resistor (say 0.5 ohm) in series to start, and then short out the resistor with a relay or MOSFET after a short delay.