Can I use a motor to make a generator?

I once heard that you can take nearly anything in electronics and use it in reverse, headphones to a microphone, a radio to an fm transmitter... well i have 2 small motors, one from a cd reader (the part that spins the cd) and one from a pencil sharpener. They are pretty straight forward... connect a battery to them and they will spin, but if find some way to have them spin, will it give me electricity back? i want to make a mini windmill... is it possible is there any other additional wiring I'll need to do? thanks...

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Chowmix126 years ago
Of course! a motor will generate electricity when spun with mechanical energy. A wind mill will work. if you want to charge batteries or such, you may want to use a diode, as it will prevent electricity from flowing backwards into the motor and causing the motor to run as if it were connected to a power source. if you have any questions, just reply!
davej6694 (author)  Chowmix126 years ago
thanks for the reply, do i need a certain type of diode? can i use an LED for one? i heard you could?
in theory, you can use an led, but that supports a very minimal amount of current to pass through. you would have to use a current limiting resistor, and that means your energy is being wasted into heat energy. I've attached a picture of a diode. you can either buy one at radio shack, or you can scavenge on off of almost any circuit board. I have seen 4 in a AC charger, or you can even try a disposable camera (free at walgreens, just ask!). desolder it and you can use it! put the black side (opposite of the white strip) on the positive side coming from your motor, and the white strip is your output. you can trickle charge batteries, or a voltage regulator for a USB charging hub! Cheers!
Have a look at the various wind-turbine projects on the site.
edwinl335 days ago

my 12v dc motor won't light even a small led light.

RahulR2173 months ago
SnehilM8 months ago
Fendic11 months ago

hi..i use dc dynamo motor to my small wind turbine..but it just produce 4.5v..how can it reach 14v ?please help me/

RelientOwl6 years ago
Of course! they're the exact same thing however if you want to charge battery's (Rechargeable's only) you will need to add resistors to the circuit.

Could you please explain further on what value resistor should I use and where it should be placed.

rickharris6 years ago
All DC motors - perminant magnet motores - will act as a generator if you drive them. You will get close to the level of power it required to drive the motor. i.e a 6 volt motor will give close to 5 or 6 volts out as a generator. BUT not a lot of current. Stepper motors work well in this.
howdie were would you find such a motor what do l look for new at this wood alt work from car thks
Stepper motors are most often found in old printers or scanners. They generally have several wires coming out of them.

A car alternator will generate about 14 to 18 volts provided you can drive it fast enough - About 3000 RPM.


i know it have been 3 years ago!!

but i still hope u can answer me

i'm planing to use a car alternator on a tesla turbine it produce more than 15000rpm

is that ok?

conorgill3 years ago
Hi, i actually tried to do this by by connecting up a battery drill to the shaft of a motor to drive it. i then connected the electric motor cable to a light bulb, unfortunately i got no power back form the motor. Can anyone tell me where i am going wrong with this??
Just bear in mind that, to generate the same voltage as the battery, you have to spin the motor at the same speed. An LED would be a bad choice for a diode, you really need something like a 1N4001 Steve
what motor should i use for a 1N4001, how many volts should it be?
If you use a diode like a 1N4001, you need more than 0.7V from the motor.
what about 1N4001& what happens if we give less input?
All you need is a diode, the thing that you need to worry about is the CURRENT rating (1N4000 series accept up to 1A), rather than the voltage. ANY conventional silicon diode will have a forward voltage drop of ~0.7V, so a source of less than 0.7V isn't going to deliver much current to the load at all.

If you are really stuck for volts, spin the motor faster, or possibly use a schottky barrier diode, which has a forward volt drop of ~0.3 Volts.

how about 1N4007& supposing i want to attach a capacitor of 1F?
Arbitror6 years ago
If those are the electric motors I think they are, you will need to create a gearbox so the windmill blades move with the most gentle winds. That must be well lubricated, and you will have to create a charging circuit, or you can buy one on the net. If you aren't using a rechargeable battery, then I don't know what you have in mind for the final outcome!
lemonie6 years ago

There is a chemical (and probably physical) principal of micro' reversibility. Which says what you say about "use it in reverse". But motors differ, and doing the reverse means knowing how the forward works for the motor you have.

Do look around here for what other people have done.