Electronic – Blinking an LED using a generator as the source of electricity

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I made a little windmill which is turning a small generator to light up an LED, but the voltage is too low even with high wind speed for the LED to glow. I thought maybe the electricity could be stored somehow maybe by a capacitor and released when the voltage is high enough, making the LED blink according to the wind speed.

I know little about electronics so I'm asking for help.
Thank You.

Edit:
What I want to know is how to make a circuit that charges up electricity from a low power source and discharge when the voltage is high enough. The frequency of discharges should increase when the power (wind speed) is increased.
About the generator. It's actually a small electric motor. I tested it with another motor, connected their rotating heads together, applied 5V to one of them and measured about 4V coming from the other, so I thought it's not a bad idea to use it as a generator. This is a really small project and it shouldn't be taken too seriously.

Best Answer

Technical Explanation: The open circuit voltage produced by your generator is too low to drive any current through the LED.

Straightforward Explanation: Your problem is probably that there aren't enough volts produced by the generator, even when the LED isn't connected. You can measure this with a simple multimeter when spinning the generator. Set the multimeter to 20V AC or DC and see what voltage you measure. To get the LED working you should see at least 1.4 volts for a RED LED, 2.5 volts for blue, or 3 volts for a white LED.

Others have suggested a resistor is necessary to prevent damage to the LED. Normally, this would be true, but in this case as the LED starts to light up, it will slow down the wind turbine, protecting itself in all but the strongest winds. Additionally, most generators have the equivalent of a resistor inside them.

One suggestion is to use a microcontroller/capacitor. The problem with this solution is you will not be able to get a high enough voltage to power up the microcontroller.

My solution:

  • Use a Red rather than white/blue LED. Use no resistor (or if you do, choose something below 300 ohms)

  • Spin the generator faster - use gears to up the speed and lower the torque if necessary

  • Get a different type of generator designed for slow speed use.

  • If you have multiple LED's, connect them all in parallel (ie. every LED connects direct to the generator)

  • Make sure you're spinning the generator the right way - test spinning it backwards, or connect the LED the other way round.

Note: Human eyes are very sensitive - if the output voltage of the generator is high enough, even a tiny current flow will cause the LED to visibly light up in the dark.

Additionally, there are many types of generator, AC/DC, brushed and brushless etc. In this situation, it doesn't really matter which you choose.

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