Event recorders employing semiconductive switching elements

Claim 1

AN EVENT RECORDER COMPRISING: A RECORDING MEDIUM FOR PROVIDING A VISUAL INDICATION IN REGIONS OF THE MEDIUM WHERE AN ELECTRICAL RECORDING SIGNAL IS APPLIED; A SOURCE OF RECURRING RECORDING SIGNALS; A PLURALITY OF ELECTRODES EACH DISPOSED FOR APPLYING AN ELECTRICAL RECORDING SIGNAL TO A SELECTED REGION OF SAID MEDIUM TO PROVIDE A VISUAL INDICATION OF AN EVENT TO BE RECORDED; AND FOR EACH OF SAID ELECTRODES A TRANSFORMER HAVING FIRST AND SECOND WINDINGS; FIRST CIRCUIT MEANS INCLUDING SAID FIRST WINDING AND FORM ING A FIRST SIGNAL CONDUCTION PATH; IMPEDANCE MEANS CONNECTING SAID SOURCE TO THE ELECTRODE AND TO SAID FIRST SIGNAL CONDUCTION PATH; SEMICONDUCTOR MEANS HAVING A SECOND SIGNAL CONDUCTION PATH CONNECTED ACROSS SAID SECOND WINDING FOR CONTROLLING THE IMPEDANCE OF SAID FIRST WINDING AND HAVING A CONTROL ELEMENT FOR CONTROLLING THE OPERATING STATE OF SAID SEMICONDUCTOR MEANS, SAID SEMICONDUCTOR MEANS HAVING A FIRST STATE FOR INCREASING THE IMPEDANCE OF SAID FIRST WINDING TO MAKE A RECORDING SIGNAL FLOW THROUGH SAID ELECTRODE TO FORM A VISUAL INDICATION ON SAID MEDIUM AND HAVING A SECOND AND