If you want to buy a dynamo torch from ebay, beware: they are most likely to be fake! Just like the one I bought: there is a crank dynamo, but there is no built-in rechargeable battery, just regular batteries. The crank works, but it only powers the leds "live", it doesn't charge anything.
I had to do something with it, so I "pimped" my torch :)
1 supercapacitor (1F, 5,5V)
Step 1: Open the Torch
First remove the "head" by pulling it. Be gentle, because the wires are thin and you don't want to break them by pulling the head off. Just pull it enough to separate it from the body about 1cm.
Then remove the 2 screws. Be careful when separating the 2 halves because the spring of the crank is very hard.
Step 2: Change the Circuit
Once you opened the beast, you have to change the connections.
Before changing the connections, it had 2 positions:
- position 1: the crank powers the leds
- position 2: the battery (3 LR44 batteries) powers the leds
After it will have the following positions:
- position 1: the crank charges the battery
- position 2: the battery powers the leds
And now, the schematics, very basic:
I have inserted a led in order to prevent the capacitor from discharging to the crank. And it turns on when the capacitor is being charged. There are many instructables already that explain this, so many thanks to You people for inspiring me in saving my fake torch!
Step 3: Put Everything Back Together
After modifying the connections, put everything back together. If you want to have some light immediately, I suggest you charge the capacitor before, putting it in the torch.
Voila! You have now a real 10 leds dynamo torch, with built-in rechargeable battery.