GB1395498A - Electric fences and voltage generators therefor - Google Patents

Abstract

1395498 Supply systems for electric fences P M ADORIAN and L P LEARNEY 7 July 1972 [9 July 1971] 32341/71 Heading H2H [Also in Division H3] A voltage generator for an electric fence 8-10 comprises a step up transformer 2, 3, a low frequency pulse generator 11 and a high frequency pulse generator 12, the pulse generators enabling bursts of D.C. pulses to be supplied to the transformer primary winding. Each low frequency pulse gates open a transistor 13 to supply the high frequency pulses via an emitterfollower transistor 14 to a transistor 15. A capacitor 16 charged from a D.C. supply terminal 7 is therefore discharged through the primary winding 2 each time a high frequency pulse switches on the transistor 15. The bursts of pulses are stepped up by the transformer and fed to the fence. In the absence of a load on the fence, i.e. in the absence of the fence being touched, the high voltage at the fence is detected by a winding 4 to switch on a transistor 29 thereby discharging a capacitor 32 and reducing the mark period of the low frequency pulses so that the transistor 13 is gated open for only a single high frequency pulse thereby reducing the drain on the D.C. supply. The pulse generators are supplied via a voltage stabilizer including transistors 27, 28. A modified form of the circuit for reducing the drain on the supply during no-load conditions is also described. A loud-speaker may be provided to give a warning when the fence is "on load".