Abstract: A capacitive discharge ignition circuit for an internal combustion engine employs a magneto generating an alternating voltage, synchronized with the operation of the engine, across its output terminals. One of the output terminals is connected to a storage capacitor which is charged during the first half cycle of the output voltage of the magneto. A thyristor is provided for forming a discharging circuit for the storage capacitor together with a primary winding of a spark plug transformer which produces a high voltage impulse across a secondary winding. The other terminal of the magneto is connected to a resistor, across which the voltage appears during the second half cycle, and to the thyristor through a diode. The voltage across the resistor is applied to the gate of the thyristor. The voltage applied to the gate is coupled to ground through the diode and the thyristor when the thyristor is fired.