Electronic Ignition: Operation: Distributor
The distributor has a toothed wheel called a reluctor in place of a conventional cam. The points are replaced by a permanent magnet, a pick-up coil and a pole piece. Signals generated by the distributor are sent to the control unit through a pair of leads. No moving parts contact each other in the distributor and there is no need for regular adjustment.
A weak magnetic field is created near the coil by the magnet. This field is strengthened when the reluctor teeth pass through it, sending a signal to the control unit. The control unit cuts off current flow through the coil primary. The amount of time current is allowed to flow through the primary (dwell) is determined by the control unit and is not adjustable.