GB1221206A - Portable defibrilator - Google Patents

Abstract

1,221,206. Portable defibrillator. WESTING- HOUSE ELECTRIC CORP. 6 Aug., 1968 [8 Sept., 1967], No. 37368/68. Heading A5R. A portable defibrillator operates on A.C. supply 10 and comprises a silicon controlled rectifier, SCR, a transformer TF, a circuit 12 for turning on the silicon controlled rectifier during one half cycle and a biasing circuit to bias the core of the transformer into saturation during the other half cycle in the opposite direction to that of the magnetisation caused in the primary winding 'by the silicon controlled rectifier. The output of the secondary transformer winding W2 is passed to the patient via the terminals T3 and T4 and a diode D3 may be provided to permit only the pulse arising when the silicon controlled rectifier has been fired to pass to the patient. Closing of the switch S1 primes the gate pulse generating circuit and the negative half cycle from the AC source triggers the signal to turn on the silicon controlled rectifier, so that it conducts current during the whole of the next following half cycle only. The gate pulse generating circuit contains a means for preventing more than one pulse 'being supplied to the patient per second. Preferably the material of the core of the transformer TF is such as will have a relatively square B-H loop.