Terry Industries, Inc.

Benito Marcel Mazza

The invention relates to a breakerless ignition system with a magneto supply for use in an internal combustion engine. The system includes a transistorized circuit for interrupting the current flow in the primary winding of the coil to thereby produce the firing voltage in the secondary which is connected to the spark plug. The circuit includes either a single transistor, or two transistors in a Darlington arrangement, connected in series in the circuit of the primary winding. A switching transistor is connected to the control electrode of either the first transistor or the Darlington pair to be adaptable to turn it off. A first resistor has one end connected to the base of the switching transistor. A parallel resistor-capacitor combination is connected in series with a further resistor, and the serial combination is connected in parallel with the Darlington arrangement or the single transistor. The junction of the further resistor and the parallel combination is connected to the other end of the first resistor. The circuit is arranged so that the first transistor, or the Darlington pair, is biased on at the start of a cycle and the switching transistor is non-conductive. The capacitor charges up, through the parallel and further resistors, to turn the switching transistor on, which in turn turns off the first transistor, or Darlington pair. The time interval elapsed before the switching transistor turns on is dependent on a first time constant formed by the parallel and further resistors and the capacitor. The capacitor then discharges through the first resistor and the base-emitter path of the switching transistor until the voltage of the capacitor reaches a predetermined value at which the switching transistor is turned off. The second time interval is dependent on a second time constant formed by the first resistor, the resistance of the base-emitter path of the switching transistor, and the capacitor.

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Ville St. Laurent, Canada

Benito Marcel Mazza