Good info, Jon! Thanks! A balancing-coil gauge uses two wire wound magnets with the needle pivot between therm. One has a constant current flow provided by either the ignition switch or a voltage-reducing circuit, and the other one has a variable current produced by running the current through the variable resistor in the gas tank. The combination of constant magnetism from one coil and variable magnetism from the other changes the position of the gauge needle. Depending on how the coils are wound and the polarity of the magnetism they produce, the needle changes position to indicate the level in the tank. It's a really a pretty simple system once the physics and electronics are understood.
Jerry
