Ignition circuit, especially for magneto-triggered internal combustion engines

Claim 1

An electronic ignition system for an internal combustion engine having at least one spark plug and a magneto having at least one magneto coil with a single low-voltage winding in said coil, said system comprising: a charging circuit connected to said winding and providing a rectified output; a discharge condenser continuously connected to said charging circuit and adapted to be charged by said output; a triggering circuit including: an electronic switch having a control electrode, and a high voltage transformer connectable by said switch, when said switch is triggered to said condenser, said sprak plug being connected to said transformer for firing when said switch is triggered by said control electrode; and a nonlinear network connected to said winding and logarithmically responsive to a signal generated therein for triggering said control electrode to effect a discharge of said condenser through said transformer to fire said spark plug whereby a firing point is automatically advanced and retarded depending upon the logarithmic response of said nonlinear network, said nonlinear network consisting essentially of: a blocking diode connected to said winding at one side of said blocking diode, a transistor having a base connected to another side of said blocking diode and two principle electrodes, a series network of a Zener diode and a resistor interposed between said other side of said blocking diode and said base, and across said base and one of said principal electrodes of said transistor, and means including a load resistor in series with the other of said principal electrodes for directly tapping a signal across said resistor and applying it directly to said control electrode for triggering of said switch.