IC engine electronic ignition system - has control transistor shunt incorporating Zener diode biased in blocking direction

The combustion engine ignition system has an a.c. signal generator, to which is connected a threshold switch. A controllable electronic ignition path interrupts the current from a direct current source, flowing via the primary of an ignition coil. The emitter-collector path of a control transistor is incorporated in a series circuit, containing also the base emitter path of a transistor serving for reversing the ignition switching path, as in 2244781. The shunt of the emitter-collector path of the control transistor incorporates a Zener diode biased in the blocking direction by the current source. The supply line from the current source to the base-emitter path of the second transistor incorporates a protective diode biased in the forward direction by the current source.