Hall Effect Sensor: Description and Operation

Fig. 38 Ignition Control Unit:

The hall control unit, Fig. 38, is a transistorized unit with two functions. It receives and amplifies the triggering pulses generated by the Hall effect switch, and it switches on and off the primary current by means of a switching transistor that is activated by the amplified signals from the distributor.
Also, the Hall control unit limits the duration of the primary current that is sent to the ignition coil. This enables the control unit to supply more current to the coil when the engine load requires it, and less when cruising or at idle. This function reduces the current draw on the electrical system, as well as extending the life of ignition system components.