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My 12v dc motor won't light even a single led light. Answered




1 year ago

What LED ? Red works best.

What direction do you spin ? try changing and let us know.

I spin it in clockwise and also in counter clockwise. But again it doesn't work.

I have to agree Yonatan24 your fingers are not powerful enough to spin the shaft, try winding some tape on the shaft to make it easier to grip.

The motor being a bad one is highly unlikely.. -.-. . -. --.

I tried also using red led but nothing works.

Put a volt meter on it. You should at least see the meter kick, if it doesn't you have a problem with the motor


1 year ago

In my videos posted yesterday there is no need to put a resistor in series with a red/green LED when you finger-spin the motor shaft (like a top for you oldsters)..

The mechanical momentum that is added to the armature is quickly dissipated as soon as the LED lights.. The LED rise in current loads the generator which slows the RPM below LED forward voltage accounting for the brief flash..

BTW the green is is accomplished by the very difficult finger-spin in the opposite rotation..

A previous stepper mini generator is included here for your purview.

Hopeful you find the time to view the Green/Red LED finger-spin video and my regrettably shaky handling of a four pole lighting a red LED video already in this thread.. -.-. . -. --.

Not powerful enough.

No, easily powerful enough for one LED, but nothing like FAST enough. Most people don't understand that the terminal voltage of a generator is achieved at the SAME speed as when its motoring at that voltage

I take it you are using the motor as a generator.

When you connect a meter to the motor do you get voltage in the first place.

Although the motor is DC it may produce AC voltage when used a generator.

This should still make the LED light up since it would act as a rectifier unless the AC current blew the LED if it reached over 20 mA.

Did you put a resistor on the LED to prevent over current.

I don't put any resistor. Looks like it doesn't produce any current.

DID you put a meter to the motor as it spins, and If you did what was the voltage?


1 year ago

This Video shows a 4 pole DC Generator and a simple Red LED...

Please note the lower speed finger-spin to light the LED.

Sorry about the shaky hands...

IMG_3382 (2).jpgIMG_3387.jpgIMG_3381.jpgIMG_3371.jpg

1 year ago

A Toy Motor as a 2 pole DC Generator, a Green/Red LED directly wired to the output.

Then the shaft is finger-spun to flash the Green LED and finger-spun the other way to flash the Red LED...

See the pic of an old style G/R LED and pic of a box of small DC motors...

IMG_3382 (2).jpgIMG_3387.jpg

Just don't provide any details at all.
Register just to post something that is of no use to anyone...
And even if people ask for details it is one by one...
Maybe by next months we will find a solution this way....

this is my 12v dc motor.


On 12V that motor probably spins at 6-10000 RPM. To get enough to light an LED, it will have to spin at more than 600 or so

I spin it using a large propeller and I know it exceeds 600rpm,


You say the LED needs 3.7V, therefore you need 3 x more speed than I guessed - that prop ain't spinning at 2000 RPM: Use some pulleys to gear it up.