AC - DC Adapter Oscillating ?

[ItsMike]

Hey guys,
I'm trying use a laptop ac adapter to power a motor. But when I connect it the motor starts up, rotates 60 degrees, stops and repeats.

The adapter is rated as 16v 4.5A and I assume it "sees" the motor as short circuit (i assume the adapter is short circuit protected) and it drops the voltage.
I do not have an oscilloscope so I can't confirm it.

Is there any way I can use this adapter to power the motor ?

 

[carbonzit]

Sounds like no. What's the motor rating? How much current is it supposed to draw?

Sounds like the power supply is going into shutdown (overcurrent or thermal), as you're asking for too much current from it. Need a bigger hammer here!

 

[Reloadron]

Is there any way I can use this adapter to power the motor ?

I don't know. Exactly what is "this motor" as in specifications would help. Also what make laptop adapter as some are 3 wire devices and not two so look at the connector carefully.

Ron

 

[ItsMike]

**broken link removed**

I though of pwm'ing the voltage with 75% DC max (16 * 0.75 = 12v) so I guess the higher voltage isn't the problem.
I wouldn't mind running the motor at a lower speed - i.e somehow disabling the over-current shutdown on the adapter ?

EDIT:

Reloadron-
Now that you mention it i've noticed the adapter input is 3 wires, but the output is 2.

 

[Reloadron]

At 12 volts the motor current should be about 1.4 Amps with no load on the motor. Overall:

Operating v : 6v - 14.4v
Nominal v : 12v
No Load RPM : 19300
No Load A : 1.4A

I realize no scope but are you monitoring the voltage to the motor when you try to power it?

Additionally, and I am not sure but I believe when you PWM you are still applying the voltage of whatever. However, the average current will be lower.

Anyway, back to now, I would guess for some reason the laptop adapter is folding over, it may not like the start load of the motor. My reference to 3 wire was on the adapter output, some have three wire outputs.

Ron

 

[KeepItSimpleStupid]

Try this. Rotate the motor by hand if you can and apply power. It may or may not start, but worth a shot.