Electric test instrument

摘要

The electric test instrument has a test probe, a light-emitting diode display and a key (A) for checking phase, neutral conductor, earth conductor and induction voltage, and a key (B) for continuity testing and for testing electric components. During mains voltage testing, the test probe is brought into contact with the phase, neutral or earth conductor respectively. In this process, the presence or absence of the phase, neutral or earth conductor are distinguished by the different indication of the light-emitting diode by not touching or touching the key (A). In the case of an induction voltage, which is radiated by a mains cable through which current flows, the light-emitting diode display shows the presence or, in the case of an interruption, the absence, when the test probe is moved along the mains cable. Table II shows how the continuity is tested in the case of resistance and the time constant (T) is tested in the case of capacitance. By reversing polarity, the forward and reverse direction are found in the case of the diode and the transistor, and the polarity in the case of the battery. One terminal of the electrical component is picked up by hand, the test probe being applied to the second terminal, simultaneously touching the key (B) with the other hand. <IMAGE>