Wind-up Torch Hand Cranked, Dynamo, LED -Amended-

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Introduction: Wind-up Torch Hand Cranked, Dynamo, LED -Amended-

Parts list

A white 5mm LED. I think it's 2000mcd, it came out of my junk box.
A red 3mm LED - high brightness. Optional. Lights when the capacitor is being charged by the dynamo.
A 1 Farad, 5.5 Volt capacitor.
A hand held crank dynamo. I got it at Jaycar electronics. I think the motor/gearbox from a simple toy car would probably work just as well.
It puts out about 5 Volts at top speed, so I thought it was a good idea to use a comparable capacitor.

Lots of patience. And coffee. And ciggies.


The switch stops the capacitor from discharging straight into the white LED, that would make it a hand-cranked light, and not a wind up, to use hands free, torch.

Step 1: The Dynamo Crank

This is the dynamo crank. Turn the handle on the side and the gears turn the dynamo, and through the magic of science, electricity comes out...

Step 2: The Little Red LED

This is the little red LED not lighting because it's really hard to crank the dynamo and take photos at the same time.

Step 3: The Little Red LED Who Could...

This is the little red LED being a team player, and lighting, to show I'm cranking the dynamo...

Step 4: Let There Be Light!

I plug the red wire into the negative terminal strip (because I'm too cheap to use a switch in something I'm only breadboarding), and Presto! Light!
Not bad for a cheap white LED, around 2000mcd I think.

Step 5: The Schematic

The amended schematic, showing the (optional) red LED facing the right way.
Sorry about the mistake, my bad.

Step 6: The Dynamo Crank Unit

Three photos that may make it a bit clearer as to how it works.
First, the unit side on.

Step 7: The Dynamo Crank Unit, Side On

Conventionally, power is applied to a motor, through the solder tabs, turning the motor and the drive shaft.
The dynamo crank works in reverse, turning the drive shaft and the motor, and supplying power through the solder tabs, to the circuit.

Step 8: The Dynamo Unit Face Up

Turning a motor spindle by hand, to generate power, is not as efficient as using a gearbox, unless you have plenty of time...

Step 9: The Gearbox End-on.

A blurry photo showing the gearbox end on.
As you might be able to see, the gearbox is used to turn the drive shaft of the motor.

Step 10: Probably Not the Last Step...

I've had to amend the schematic because I'd put the red LED in the wrong way around.
Thanks to LasVegas for pointing that out.

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    31 Comments

    Great eco design! My only question is, Where did you get the gear settup and crank from? Did you make that yourself or did you just steal one from something else?

    Great eco design! My only question is, Where did you get the gear settup and crank from? Did you make that yourself or did you just steal one from something else?

    will a normal toy motor really work??? im not sure.....
    plz comment/reply

    The small LED has to be backwards. It's to stop the capacitor discharging back into the motor. It looks wrong, I know, but it does work.

    That's what I mean. It has to have the cathode (flat side) on the positive side of the capacitor to allow charging of the capacitor and prevent discharge through the generator. If you follow the path of discharge with the switch off, you'll see that the schematic has both LEDs with the same polarity.

    You built the circuit right. You just made a minor error on the schematic. The attached (corrected) schematic shows the charging path of current (blue) and the discharge path (red). As you can see, as in any diodes, current flows into the LED's cathode against the arrow. This is a carry-over of the pre-transistor belief that current flowed from positive to negitive.

    Picture 3.png

    thanks and please launch the right schematic or instructables

    Thanks. I stand corrected. I'm not too bad with a soldering iron, but my theory work is terrible. Appreciate the input.

    Where can you get these capacitors!!! I can't find many suppliers in the UK, so if anyboady knows of any cos i really gotta get my hands on some (Or if anyone knows what electric appliances have these caps in). Or i think some USA company could ship one to me.....

    4 replies

    have you tried maplins or Radioshack altho i think raidio shack is american

    Thankyou so much dean-101! i shall get one bought for me lol as its my birthday on the 24th! :) thanks

    no problem. if you are also loooking for cheap leds or resistors goto ebay and find a shop called "sure electronics" they sell 100 ultra bright LEDS with resistors for £10 and you can get blue, uv ,red ,green or white. they also sell Micro controllers, solar cells, laser, tools and everything to do with electronics very cheap.

    + for details - for mention of cigarettes

    1 reply

    Uhm... what's the issue with mentioning cigs, it's one word in 10 pages of instructables ... @least he didn't dedicate a whole article on such an apparently offensive subject.

    Why isn't there any regulation??? Wreck your LED's.

    Wait, tell me if I'm wrong, the dynamo is basically an electric motor that you turn so electricity is produced?

    I really thought dynamo's were something totally different (if I'm right).

    That means I can use any electric motor I have here and use it to power electronic thingys? That'd be cool (try dismantling an old matrix printer, LOTS of useful motors in there. ..too much in fact)

    2 replies

    it works on most dc motors but not sure about ac motors

    Ac motors have two coils not one coil and a permanant magnet, so no it would not work.