| 摘要 |
An alternating voltage, the frequency of which is suitably between 5 kHz and 20 kHz for achieving a high efficiency, is applied to the conductors of a, for example, single- or multi-layer circuit board, which conductors are connected to one another by a short circuit. To keep down the influence of disturbing parallel capacitances, the audio-frequency alternating voltage is preferably superimposed on a direct voltage. To determine the course of the circuit closed by the short circuit, the magnetic field occurring along the conductors through which the current flows is detected by means of a movable electromagnetic probe (40). The signal occurring at the output of the probe, the amplitude of which changes as a function of the distance from the conductors through which the current flows, is rectified in a rectifier (42) and then used for generating a control voltage which drives a voltage-controlled oscillator (46). The output frequency of the voltage-controlled oscillator (46), which changes as a function of the amplitude of the output signal of the probe (40), is supplied to an electroacoustic transducer (50). The maximum output frequency of the voltage-controlled oscillator (46) is preferably 1.5 kHz. Since the human ear responds very finely to frequencies within the range up to 1.5 kHz, the conductor through which the current flows can be very easily and correctly traced, and the short circuit located, by moving the probe (40). <IMAGE>
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