Transistor-s.c.r. circuitry providing a thyratron equivalent

Claim 1

A SOLID STATE SWITCHING APPARATUS CAPABLE OF BEING UTILIZABLE IN A CIRCUIT AS A DIRECT SUBSTITUTE FOR A THYRATRON, SAID APPARATUS COMPRISING: (A) AN ENVELOPE STRUCTURE PROVIDED WITH AT LEAST FIRST, SECOND AND THIRD TERMINALS ADAPTED TO BE RECEIVED BY CONVENTIONAL THYRATRON-RECEIVING TERMINALS AND CORRESPONDING DIRECTLY TO THE ANODE, CATHODE, AND CONTROL GRID TERMINALS RESPECTIVELY OF THE THYRATRON, (B) A SILICON CONTROLLED RECTIFIER MOUNTED WITHIN SAID ENVELOPE AND HAVING A RELATIVELY HIGH POWER HANDLING CAPABILITY AND RELATIVELY LOW INPUT IMPEDANCE WITH RESPECT TO THE THYRATRON, (1) SAID SILICON CONTROLLED RECTIFIER HAVING ANODE, CATHODE AND GATE ELECTRODES. (C) A TRANSISTOR MOUNTED WITHIN SAID ENVELOPE AND HAVING RELATIVELY LOW POWER HANDLING CAPABILITY AND RELATIVELY HIGH INPUT IMPEDANCE WITH RESPECT TO SAID SILICON CONTROLLED RECTIFIER, SAID TRANSISTOR HAVING FIRST, SECOND AND BASE ELECTRODES, (D) SAID FIRST AND SECOND ELECTRODES OF SAID TRANSISTOR BEING CONNECTED SO AS TO DEFINE A PATH IN SHUNT WITH SAID ANODE AND CATHODE OF SAID CONTROLLED RECTIFIER, (1) SAID SHUNT PATH INCLUDING SERIES RESISTANCE, (E) SAID FIRST ELECTRODE OF SAID TRANSISTOR BEING CONNECTED TO SAID GATE ELECTRODE OF SAID CONTROLLED RECTIFIER, (F) SAID ANODE AND CATHODE ELECTRODES OF SAID SILICON CONTROLLED RECTIFIER BEING COUPLED TO SAID FIRST AND SECOND TERMINALS RESPECTIVELY, AND (G) SAID BASE OF SAID TRANSISTOR BEING COUPLED TO SAID THIRD TERMINAL.