Start-to-run circuit for an electronic ignition system

A start-to-run circuit suitable to be utilized in an adaptive dwell ignition system for an engine having an adative dwell capacitor which provides a dwell control signal that varies the excess dwell time in response to variations in engine rpm, an amplifier which is rendered conductive in response to the dwell control signal during each firing cycle period to provide dwell current to charge an ignition coil and a feedback circuit for limiting the dwell current to a predetermined magnitude prior to discharge of the coil, comprising:

• start dwell circuit means coupled with the adaptive dwell capacitor which is responsive to the ignition system being in a start mode of operation for charging and discharging the adaptive dwell capacitor for producing a first logic signal at an output thereof during a predetermined interval of each firing cycle period;
• logic gate means coupled with both the ignition system and said output of said start dwell circuit means which is responsive to said first logic signal for providing first and second output signals, said first output signal rendering the amplifier conductive and said second output signal being produced while the dwell current is not being limited by the feedback circuit;
• and
• logic circuit means coupled with the ignition system, said start dwell circuit means and said logic gate means which is responsive to a start command signal supplied thereto at an input for causing said ignition system to be in a start mode of operation, said logic circuit means being responsive to the termination of said start command signal in combination with receiving said second output signal from said logic gate means for inhibiting said start dwell circuit means and causing the ignition system to transition to a run mode of operation only during a predetermined period of the firing cycle period wherein said logic gate means is enabled by the ignition system. PG,16