Ingnitor for internal combustion engines

Claim 1

An ignition device for an internal combustion engine having spark gap means and a shaft rotatable in synchronism with the rotation of the engine, comprising a transformer having a primary winding and having a secondary winding for connection to the spark gap means, a permanent magnet attached to said shaft so as to be rotatable therewith, a stationary magnetizable yoke structure disposed adjacent to said rotatable magnet structure and having a field gap, said rotatable magnet and said yoke structure conjointly defining a magnetic circuit for providing a magnetic field having an intensity that changes between values thereof in synchronism with the rotation of said shaft and said engine, a galvanomagnetic resistor disposed in said gap and having a resistance changeable in response to changes in said magnetic field, and an amplifier comprising a voltage divider, a switching transistor and a power transistor connected in cascade, said voltage divider consisting of two two-pole members, one pole of one member being joined to one pole of the other member so as to form a tap, one of said members being said galvanomagnetic resistor and the other of said members being a fixed resistance, said tap being connected to the base of said switching transistor, the other of said poles of said one member being connected to the collector of said switching transistor and the other of said poles of said other member being connected to the emitter of said switching transistor to convert the collector current of said switching transistor changes to pulses in response to said changes in said galvanomagnetic resistor, said switching transistor and said power transistor conjointly defining a shaping network for increasing the steepness of the edges of said pulses, said power transistor being connected to said primary winding of said transformer, whereby said power transistor interrupts the current in said primary winding in response to said pulses.