IC engine ignition circuit with extra transistor - has precise limiting of current flowing through output transistor and transformer primary

摘要

The ignition circuit, for an IC engine, has the control transistor base (9) connected via the emitter/collector path of an auxiliary transistor (11) to the emitter of the output transistor (7). The auxiliary transistor collector is connected to the control transistor base. The auxiliary transistor base is earthed via a diode (12) and resistor (13). The advantage lies in being able to precisely limit the current flowing through the output transistor base/emitter junction and therefore the current flowing via this transistor collector/emitter path through the transformer primary winding.