Overheating protection circuit for IC engine ignition transistor - has temp. sensor on power switch controlling hold time of timing circuit

摘要

The protective turn-off circuit turns off a power transistor switch in the primary circuit of an i.c. engine's ignition system. A temp. sensor (17) is mounted on the power switch (13) and controls the hold time of the timing circuit (16) so that the switch is turned off when its temp. exceeds a safe limit. The relation between temp and hold time is hyperbolic. The timing circuit controls the switching of the switch.