| 摘要 |
A voltage detector particularly suitable for a portable type lineman's detector comprises an electrically insulating casing, a metal probe having a rear portion inserted into the casing and a front portion projected from the casing, a field effect transistor, a gate electrode of which is coupled to the rear portion of the probe, a transistor having a base connected to a drain electrode of the field effect transistor, a light emitting diode connected in series with an emitter-collector path of the transistor, a D.C. battery means connected across a series circuit of the emitter-collector path and the light emitting diode and a high input resistor connected across the probe and a first junction point between the light emitting diode and the D.C. battery means, wherein a source electrode of the field effect transistor is connected to a second junction point between the transistor and the light emitting diode. When the front portion of the probe is made contact with a conductor with or without inserting insulating body therebetween a voltage is induced at the gate electrode of the field effect transistor so as to make conductive the transistor and the light emitting diode produces light which can be seen from the external of the casing.
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