Disclosed is a test device. The test device according to an embodiment of the present invention is operated by a power supply unit provided to be portable, and tests a sensor device using an alternating current of a high frequency. Therefore, the portability and operation reliability of the test device are improved, and the convenience of use can be improved since a separate wire member or the like for the operation of the test device need not be provided.

Disclosed is a test device. The test device according to an embodiment of the present invention is operated by a power supply unit provided to be portable, and tests a sensor device using an alternating current of a high frequency. Therefore, the portability and operation reliability of the test device are improved, and the convenience of use can be improved since a separate wire member or the like for the operation of the test device need not be provided.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.