Electric motor as a generator, DC type?

[Johnson777717]

alright, I'm goofin around a little bit, but I have a serious question, if I may?

I'm making a little generator out of an electric motor which has a fan blade attached to the shaft of the motor. Basically, I just want to make a little wind generator to power a device that lights an LED when the air conditioning unit is on.

I have a circuit in mind, but I wanted to ask a question about the type of DC electricity that the generator will be creating. I know that a generator will create a certain type of DC electricity, but I don't know what type this is, and if I need any specific type of circuit to convert this into regular DC electricity.

Basically, I just want to hook the generator up to an LED (with a resistor if necessary). I'm not sure what kind of RPM's I need to create a specific voltage / amperage but I'll figure that out.

Does anyone know about the kind of DC electricity an electric motor will generate?

Thanks a bunch!

 

[bmcculla]

There is only one type of DC electricity. A DC brush motor will make a DC voltage with a bit of ripple due to the connection- disconnection of the brushes. The addition of a capacitor accross the LED should eliminate this effect. Other than that The only problem would be if the motor was spun too fast and ran too much current through the LED.

Brent

 

[Johnson777717]

Thanks for the input Bmculla. The motor that I'm going to use is brushless. Would that have any effect on the output, or would this still be similar to a brush motor?

 

[bmcculla]

A brushless motor won't generate DC. It'll generate a sine wave for each phase (unless there's a type I'm not familiar with). Your best bet is to just buy a cheap brush motor. You should be able to get one for under a dollar.

Brent

 

[Styx]

if you have a brushless it is fine. Just pass the terminals through a rectifier (of appropriate phase leg length) to get DC and also smoothing cap

--EDIT--

Also a Brushless DC machine does not give out a sinusoidal backEMF it is trapisoidal so once recified it will be closer to DC that the backEMF of a syncrouns machine.

 

[laroche73]

Stepper motors

This link adds to the discussion and should probably be included as part of this thread

https://www.electro-tech-online.com/threads/xt-caps-to-stock-for-pic-tinkering.5980/