A “step-down” auxiliary voltage regulator drives the fuel and temperature gauges on GL1000s. This clever device provides a constant 7V input voltage to power these gauges. This effectively buffers the wide normal fluctuations in battery voltage. Without the step-down regulator, your gauge readings would be very unreliable because main battery voltage varies with rpm, load, stator output and accuracy of the voltage regulator. Many older cars use this same technology for the dashboard.
7 Volt Auxiliary Regulator