Monday, 23 December 2013

Build a supercap circuit to keep your dynamo powered tail light on at the stop lights

Because cycling at night is dangerous.
Because dynamo powered lights rock.

With this little mod, you will be safe while stopped at the crossings: its supercap will keep the led(s) lit while you wait for your turn.

The circuit on the left uses a clever technique to limit the current and increase the voltage: a charge pump. My only regret is that it uses a linear regulator to keep the voltage at 5V.

While this is obviously inefficient, it works and with a hub dynamo you will probably never feel the difference.