Noise protection circuit for heart pace maker - has de-coupling stage using diode in series with transistor collector-emitter path

摘要

The noise signal protection circuit eliminates the effect of continuous, pulsed or modulated noise signals using a de-coupling stage (20) between the output circuit (12) and a pair of clamp terminals (16,18). Pref. the de-coupling stage (20) uses a diode (D1) in series with the collector/ emitter path of a transistor (T1) between the output circuit (12) and one clamp terminal (16), the transistor base coupled to the other clamp terminal (18) via a base resistance (R1). Pref. a second diode (D2) in series with a collector/ emitter path of a transistor (T2) is coupled between the clamp terminals (16,18), the transistor base controlled by a monostable flipflop activated by the pulses from the output stage (12).