Pulser Coils

The pulser coil is a very simple component. It is generally housed in a small plastic container, and internally potted with epoxy or some other oil resistant material. The pulser coil itself is made up of a small magnet (the exposed metal you can see on the front of the housing), which is wound with a coil of very fine wire. The pulser coil may have one or two wires exiting the case to connect to the ignition box. On one wire systems, on side of the internal coil is grounded to chassis ground through the mounting hardware. On two wire systems, a wire from each side of the coil exits the case to connect to the ignition box.

The pulser coil generates it's timing pulse with help from the flywheel . The outside diameter of the flywheel has at least one timing mark, which consists of a raised ridge, spanning some percentage of the outer edge of the flywheel. This ridge is pronounced, and has sharp leading and trailing edges. The Pulser Coil is mounted to the engine sidecase in very close proximity (some thousands of an inch) to the flywheel, spaced to be extremely close to the timing ridge(s). The timing ridge is referenced to the Top-Dead-Center (TDC) piston location inside the engine. As the timing ridge on the flywheel spins past the pulser coil, the timing signal is generated. The leading and trailing edges of the raised metal ridge produce a low current, high voltage pulse, either positive then negative polarity, or negative then positive, depending on the direction of the coil winding inside the pulser coil. The ignition box then uses this signal to reference the piston location, and given it's inputs (RPM and TPS) it will determine the correct time to fire the spark plug, by discharging the internal capacitor out to the ignition coil, and finally the spark plug.