Abstract: An improved high voltage pulse power supply for a spark plug test fixture. AC line voltage is applied through a voltage step-down transformer, a half wave rectifier and an electronic switch to the primary winding of a conventional ignition coil. During the rise time of positive half cycles, the rectified voltage is applied through the electronic switch to the ignition coil primary. As the positive half cycle begins to fall towards the zero crossover, the electronic switch is opened. The magnetic field collapse in the ignition coil produces a high voltage negative pulse which is applied to a spark plug under test. The peak voltage of the negative pulse is adjusted by controlling the peak current in the ignition coil primary.

Abstract: Apparatus for electronically modifying spark advance and dwell in a spark-ignited internal combustion engine. Conventional cam driven breaker points on the engine are initially set for the desired maximum spark advance. The signal from the breaker points is electronically delayed to reduce the spark advance by a predetermined constant value independent of the engine speed. Dwell is also electronically controlled to a predetermined constant value independent of the engine speed.

Abstract: Apparatus for measuring the temperature of the insulator tip of a spark plug being operated in an internal combustion engine. A thermocouple is embedded in the surface of the insulator tip adjacent the spark gap for sensing temperature. The output of the thermocouple is connected through an electro-optical ignition voltage isolation circuit to circuitry which maintains a substantially constant temperature signal during the time interval that ignition voltage is applied to fire the spark plug. The temperature signal may drive a temperature indicating display or devices such as chart or tape recorders to produce records which may be used in analyzing either operation of the spark plug or combustion.