Abstract: The invention refers to a device for an electric fence. The device include an electric unit (1) which is connectable to an electrically conducting fence (2) and which includes a voltage generator (4) arranged to apply a relatively high electric voltage to said fence (2). Furthermore, the device include a proximity detector (5), which is arranged to sense a state at which an animal is at least in contact with or in the proximity of said fence (2), and a control unit (6), which is connected to the voltage generator (4) and the proximity detector (5) and arranged to activate the voltage generator (4) to apply the relatively high electric voltage to the fence (2) in response to the state. The proximity detector (5) is arranged to detect the state by sensing an electric parameter, which substantially depends on the capacitance between the fence (2) and ground.

Abstract: The present invention discloses a method and a device for conversion of an optical data signal from a multimode fibre (1), which except for normal data signals may contain interruptions and an overmodulated low frequency signal, to a corresponding signal which is transmitted further into a single mode fibre (8) by a laser (7). An electric signal from an optical receiver (2) partly directly and partly through a low pass filter (4) is coupled to a comparator (5) the output of which modulates the laser (7). Upon detection of an optical interruption the low pass filter (4) is influenced such that its output signal is stored in a memory device, and the laser is influenced by diversion of the laser current, simultaneously as an analogue value in the control loop of the laser is stored. When the interruption ends both the laser transmitter (7) and the low pass filter (4) continue to operate as before on the basis of their stored analogue values.