T53 – Ignition Exciter Unit

Identification and Location

The ignition exciter is mounted to the forward face of the air diffuser at the 10 o’clock position.

System Design

The ignition exciter is a dual output, capacitor discharge type unit that converts low voltage to high voltage through a transformer
and a vibrator. Input power, at a nominal 24V DC and 3 amperes, is applied to the ignition exciter and is directed to the radio-frequency noise generated by the ignition exciter. This filter relies upon the inductor-capacitor combination to tune the response of the filter system for maximum effectiveness. A mechanical vibrator converts the steady state to input power to pulsating DC power suitable for voltage multiplication by the transformer. This transformer increases the pulsating DC from 24 volts to the 2500 volts suitable for charging the capacitor system. The vibrator operation is quite simple, in that the incoming current passes through the primary coil and the vibrator points to ground. This current flow creates a magnetic field in the transformer core between the coils, thus attracting the vibrator reed upward. This action breaks the circuit, the field collapses, and the reed falls back to the position shown. This cycle repeats, and the result is a pulsing DC current in the primary coil, which is converted to a stepped-up voltage on the transformer secondary coil. The current developed on the transformer secondary coil is rectified by a semiconductor diode and then stored on the capacitor shown immediately after the rectifier diode. When the charge has built up on the capacitor to the point where the voltage across the capacitor has reached the trigger point for the calibrated spark gap, the capacitor discharges through the gap into the spark splitters and to each of the four ignitors.