| 摘要 |
A temperature controlled ignition circuit includes a high voltage coil, ignition circuitry connected thereto and a magnetic generator for controlling the operation of the ignition circuitry and the production of a high voltage at the coil. A transistor in the ignition circuitry is connected at its base to one terminal of the magnetic generator and is biased for full conduction upon provision of some predetermined positive voltage by said generator. A second transistor having operating characteristics similar to those of the first is connected to operate as a diode; i.e. with the base electrode being connected to the collector electrode thereof. The second transistor is connected between ground potential and the other terminal of the generator and is biased into forward conduction to maintain a reference voltage at the other terminal of the generator substantially equal to that at the base-emitter junction of the first-mentioned transistor such that the average current densities of both transistors are substantially equal. Thus, any change in the reference potential at the base-emitter junction of the first transistor due to temperature will be compensated for by a similar change in the reference potential at the other terminal of the generator so that the first-mentioned transistor operates upon application of the predetermined voltage by the generator despite temperature and/or power supply voltage changes. The predetermined voltage corresponds substantially to the zero crossovers of the generator output. The dynamic impedance of the second transistor is lower than the dynamic impedance of a conventional diode and as such does not raise the impedance at the base of the first transistor as would a conventional diode. |
