Patent ID: 7730879

Claim:
A voltage transformer circuit for supplying ignition power to a spark plug comprising a forward converter comprising a transformer comprising a primary side and a secondary side, which are coupled via a transformer core, a primary circuit, in which the primary side of the transformer, connections for a primary voltage source and a transistor switch for engaging the primary voltage U 1 are arranged, and a secondary circuit, in which the secondary side of the transformer and connections for a spark plug are arranged, wherein the primary circuit is coupled with the secondary circuit via the transformer in such a manner that, when the transistor switch is closed, power is transmitted from the primary circuit into the secondary circuit, the primary circuit comprises a discharge path, via which the transformer can be demagnetized when the transistor switch is open and via which power can be retransmitted from the secondary circuit for shortening the duration of an arc discharge, and the discharge path forms a demagnetizing circuit with the primary side, which is configured by means of a diode in the discharge path in such a manner that power can be prevented from being transmitted from the demagnetizing circuit into the secondary circuit, the diode preventing a current emanating from the primary voltage source from flowing through the discharge path when the transistor switch is closed and permitting a demagnetizing current for demagnetizing the transformer to pass when the transistor switch is open.