Wednesday, April 4, 2012

Powering speakers, etc with a bike dynamo

I recently got rid of an old Pioneer receiver in favour of a tiny Class D amplifier. The class D amp is more efficient, sounds better and is approximately 10x cheaper. Did I mention, it's tiny?

While shopping for a variable voltage regulator for a power supply I discovered that EBay sells fun-looking 1.5V-26V regulators...for $10. I've been eyeing the Busch + Müller E-WERK universal power supply(up to 13.5V) for a while now, but those sell for $110. It's no fun spending a hundred bucks on a bike accessory that may not prove useful. I had no choice but to buy the EBay regulator.

As my first experiment I tried powering a 12V MR16 light... it worked, but flickered like mad. A fat capacitor on the regulated side calmed the flicker. Great, now I can use indoor lights to illuminate my outdoor bike rides.

Next I tried a 1-meter 12V LED strip, the strip uses a lot less current than the light bulb so it was quite happy.

Then I wondered...could I power decent speakers using dynamo power? $8 ebay amp later...yes I can!
Recipe: dynamo -> rectifier bridge -> high voltage smoothing capacitors -> regulator -> 16V 0.1F cap -> (optional voltmeter) -> ta2024 amp -> speaker[s]

By the way, do not buy this ta2024 amp, spend a few dollars extra and get a board with proper audio in. I had to desolder the weirdo 3pin connector and solder on a home-made audio cable. It also comes with extremely crappy capacitors and crappy terminals for remaining connections (vs decent stuff on the $14 ta204 amp).

I think this voltage regulator will prove very handy for bike touring + camping. Should be especially fun once I combine the dynamo with a 3.5W solar panel. Buck/boost will prove very handy indeed.