Electronic contactless test equipment for electrified cattle fence - detects electromagnetic field radiated from fence during voltage pulses and gives synchronous audible and visual indications

摘要

An insulated double Cu wire antenna (A) detects the voltage pulses applied to the fence. The signals from the antenna (A) are supplied to a two-stage transistor amplifier (V1,V2). The amplified pulses are evaluated by an integrated logic circuit (IC) from which two outputs are forwarded (1) to a piezoelectric speaker (W,2) via a low-power transistor driver stage (V3) to a light-emitting diode (LED). The appts. is powered from a battery (B) with an on/off switch (T). Optical and acoustic indications are given at the frequency of the pulses. ADVANTAGES - It is not necessary to drive earthing spike into ground near every test point. Labour of checking long fence is reduced, and risk of electric shock to tester is avoided.