Transistorized ignition system for internal combustion engines

Transistorized ignition system for an internal combustion engine have an ignition coil (6);

• a main switching transistor (7) connected in series with the primary (5) of the ignition coil (6);
• an ignition breaker switch (11) connected to and controlling conduction or blocking of the switching transistor (7) in accordance with commanded ignition events;
• a control capacitor (12) connected to the switching transistor (7) to control the switching transistor to non-conduction or blocked state if the engine should be stopped, with the ignition breaker switch (11) closed;
• a control resistor (16) connected between the positive (3) and negative (4) terminals of a source (1) and in series with said breaker switch (11), the junction (17) between said control resistor (16) and said ignition breaker switch (11) being connected to the control capacitor (12);
• a charge discharge resistor (14) forming a series connection (15) with the ignition breaker switch (11) and the control capacitor (12) between the positive (3) and negative (4) terminals of a direct current source (1);
• a capacitor discharge circuit (18) connected to the control capacitor;
• means connected to the control capacitor (12) and gradually changing over the conduction state of the main transistor (7) from conduction to blocking to prevent induction of a high-voltage pulse in the secondary (9) of the ignition coil (6) after the engine has stopped, comprising
• an auxiliary transistor (13) connected to the control capacitor (12) and a control circuit therefor gradually changing the conduction of the emitter-collector path of said auxiliary transistor, the main switching transistor (7) being connected to and controlled by said auxiliary transistor and similarly gradually changing to blocking state in dependence on the gradual change in conduction of the emitter-collector path of the auxiliary transistor (13);
• a coupling transistor (32, 38) connected to and controlled by said auxiliary transistor, annd having its emitter-collector path connected in parallel to the base-emitter junction of the main switching transistor (7);
• and wherein the collector of the auxiliary transistor (13) is connected to the positive terminal (3) of the source (1) -- the emitter is connected to the negative terminal (h) of the source (1);
• and the base of the auxiliary transistor (13) is connected to the capacitor discharge circuit the auxiliarly transistor (13) providing a control output through said coupling transistor (32, 38) to the main switching transistor (7).