Dc Generator principle???

[silvarblade]

i had a plan of making a very simple wind generator but the problem is that i cant generate the dc voltage from the motor of my old PC power supply. is there some safety device installed in the motor . i gave it air from a hair drier and it did not even give a one volt reading on the voltmeter. the motor is 12v Dc .14 amp motor. a picture is given below

 

[Nigel Goodwin]

It's probably a DC brushless motor, so won't work as a generator.

 

[dknguyen]

It's PC fan which almost 100% means that it uses a brushless motor. That means to make it output a DC voltage you will need a diode rectifier to rectify it's (usually 3 phases) and an output capacitor to make a DC voltage- otherwise you would get 3 wires making some kind of AC or trapezoidal voltage waveform.

But the other thing to remember is that a brushless motor doesn't run on it's own...and all you need to do to run the fan is apply power to it- that means the fan has it's own electronics inside it which are protecting the electronics from the motor's generator effect which means the generated power won't appear the fan's power terminals.

So at the very least, you'd have to crack open the fan and get rid of those electronics (most PC fans are brushless motors and so most have some electronics inside).

 

[k7elp60]

It's probably a DC brushless motor, so won't work as a generator.

To add to what Nigel says. There is probably electronics inside the case of the motor that converts the DC input to AC to turn the motor. I have taken a few old ones apart and seen the electronics.