2014-07-18

Dynamo Torch Upgrade with LED

      This is a very old project back in 2005, when LEDs were not so wide spread. I decided to transform a standard dynamo torch, and replace the bulb with LEDs. My idea was that since the LEDs need less energy for bright light, the torch will give more light with less pushing.
I found the idea and the schematics on the Internet, but now I am unable to find the web site, although I searched a lot. Perhaps it does not exist any more.

Instead of 4 rectifying diodes, I use only 2 diodes and 2 capacitors, and this schematic doubles the output voltage, which is very useful for the LEDs. Schottky diodes are used because their voltage drop is very small.

Here are some old pictures, unfortunately I don't have many:


Soldering all 5 white LEDs (they were only 5Cd) on a cardboard circle. Now I have even 30Cd.

Before that I glued one side with aluminum foil, to reflect some light.

Two capacitors are a part of the voltage doubler, the third one is just for stabilizing the voltage a little bit. They are 2200 micro F, 16V.







I used 2 very small metal plates to solder and extend the thin cables that come out of the dynamo, because if you operate a lot with them, you can easily damage them.

Here is the schematic:


Vac0 is the dynamo.
It is possible to omit C2. In that case the LEDs will light up faster, but they will also dim faster!

Regards


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