What is it?

A small PCB which takes the AC voltage of a bicycle hub dynamo (6V, 3W) and turns it into a stable 5V DC voltage to use for e.g. charging USB devices and powering other electronics on the bike. If you have an Arduino project or other that goes on a bicycle, this could be your power source. Note: works with 6V/3W hub dynamos only, no bottle dynamo or higher voltage hub dynamo!

Input through a JST XG 2.54mm connector. Output through a JST SH 1mm connector or 2.54mm solder pads provided.

Why did you make it?

It was used in a project where GPS trackers in a bike were kept charged using the hub dynamo.

What makes it special?

It's very efficient, and small measuring 18mm x 14mm x 44mm. This allows it to be built inside the bike frame for example. In order to minimize losses in traditional diode-based full bridge rectifiers, it uses a MOSFET based approach. After rectifying, a low-dropout regulator (LDO) is used to further minimize losses.

Footnotes

Manufacturing and component sourcing for this product was done entirely in the UK. Thousands of units were produced for the project, and these are surplus stock left over after the project was completed. All proceeds for the sales of products in this store go fully to efforts to preserve and expand forests.