I built a simple circuit that will act as a charge indicator. Using a NAND gate for logic and sensing the 12V Charging signal line from the voltage regulator (divided down to 5V for TTL), this circuit will illuminate a red LED when no voltage is present on the regulator Charging signal line, but will turn the LED off once the dynamo is charging. Rather than simply rely on the volt meter for electrical system status, this LED indicator will let me know immediately if the charging system fails.
