GUARDS DEVICE Russian patent published in 1994 - IPC

FIELD: technical means of guards. SUBSTANCE: device has signal wire 1 (which is broken if trespasser is in the control zone). Electric circuit of the wire is controlled by means of power supply 2, resistive element 5 and threshold unit 6 which has output connected with input of signalling unit 7. The voltage exceeding over threshold level is kept constant in the output of threshold unit 6 due to introduction of voltage limiter 3 and capacitive member 4 into the device when powerful pulsed electromagnetic disturbances are present or in case if short-time break in contact is observed in points of connection the signal wires are twisted. EFFECT: improved noise immunity. 1 dwg