Dynamo Hum: Off With The Bloomers

Apologies to Zappa this time. ┬áThe other day I bought a small LED dynamo flashlight; I was curious about the implementation details and how much power it actually generates. ┬áTurns out the dynamo appears to be a very common sort of DC motor and, while it doesn’t appear to produce a lot of power, it does seem to be a usable amount for a variety of low-power applications.

First peek: it’s geared up quite a lot; speaking of quite a lot, there’s some silicone grease in there too…

The dynamo motor appears to be identical to the one that drives the tray mechanism of every CD or DVD drive I’ve ever taken apart. (Not just physically, I got similar voltages from finger-spinning each of them)

Starting from the left: a bridge rectifier so it doesn’t matter which way you turn the crank, the resistor that (I believe) limits the charging current into the battery, the flashlight / charge switch (yup, you gotta crank in the dark), the LEDs and their current-limiting resistor, and finally a cute little 3-cell NiMH battery pack.

The bottom of the circuit, showing the traces.

Sooner or later, I’m going to play with dynamos again, they seem like a great way to power small projects, need to learn more about battery charging first though.

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