| 摘要 |
PURPOSE:To facilitate the confirmation of a current supply state, by interposing two kinds of light emitting elements different in a current supply direction in a curcuit connected to two resistors each equipped with two connecting terminals which are connected to the power source of a car so as to be connected in series and connecting the connecting points of both resistors and a probe. CONSTITUTION:Alligator clips 2, 2 are connected to a battery being the power source of a car. Either one of terminals may be connected to an anode but the remaining terminal is connected to a cathode. By this connection, a current is supplied to two resistors 4, 4 and, in this example, a current of about 10mA is generated while a connecting point 5 is held to potential of 6 volt and this potnetial comes to the reference voltage of operation. When a probe 10 is brought into contact with the positive potential place of the electric circuit of the car, especially, to the output terminal of the dynamo having high potential of the car, an element 11a emits red light because potential is usually about 18 volt because the potential in the side of the probe 10 is high. When the probe 10 is brought into contact with an earth circuit, an element emits green light because the potential in the side of the probe 10 is low.
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