Temp.-stabilised electronic ignition for IC engine - has series opposition Zener diodes between base of control transistor and earth

摘要

The primary current in the coil is controlled by a transistorised circuit (2) between the coil connection and earth. The input of the transistor stage has two Zener diodes (3,4) between the input and earth and parallel to the emitter resistance (6) connection to earth. The Zener diodes are in series opposition and have temp. coeffts. similar to the components of the transistor stage. The variation of voltage through the Zener diodes, due to temp. changes, is balanced by the changes in the emitter resistance and the emitter-base voltage. The variation in drive for the coil is reduced to approx 5 per cent as compared with 30 per cent for non-compensated ignition circuits. ADVANTAGE - Improved ignition control, less susceptible to temp. changes.