Internal combustion engine ignition system with improvement

Claim 1

In combination, an internal combustion engine having a crank shaft and a fuel control arm and an electronic ignition circuit, said ignition circuit having a transformer with center tapped primary winding forming an oscillator to develop a continuous high-voltage AC type spark signal of variable duration, said circuit including a control winding on said transformer for starting and stopping said oscillator and electronic switch means comprising a controlled rectifier for starting and stopping said spark signal, and control means for said controlled rectifier, comprising a transistor network having an input for receiving ignition control pulses in timed relation to said crank shaft and an output for controlling said controlled rectifier, said transistor network comprising means for cutting off said controlled rectifier to start said spark signals in timed relation to said crank shaft, said transistor network also comprising means for actuating said controlled rectifier to conduct in order to stop said spark signals after a variable time interval inversely related to the speed of said engine, said transistor network having circuit constants to provide a duration of said spark signals having a predetermined number of degrees of crank shaft rotation, and said transistor network also comprising means for varying one of said circuit constants to control said variable time interval, comprising a variable resistor, a coupling to said fuel control arm for varying said variable resistor, and a fixed resistor in series with said variable resistor to determine a minimum number of degrees of crank shaft rotation.