| 摘要 |
<p>PURPOSE:To obtain an electronic direction indicating device which has a circuit for detecting disconnection of a load without an adjusting resistance and is excellent in mass productivity by detecting presence of an indicator lamp as a load to be connected to semiconductor switches through resistances and diodes and by taking it out as a disconnection detection signal. CONSTITUTION:A resistance 6 is connected to a negative or a positive input terminal of a comparator COM and a positive terminal of a battery H, and diodes 7 and 9 are connected in the reversed polarity of the continuity direction of semiconductor switches G and F, respectively. If an indicator lamp K or J is disconnected, when the semiconductor switch or G is off, a resistance 10 or 8 and the diode 9 or 7 are not grounded, and the negative input of the comparator COM is brought to the H level. The Hi level in these two cases is taken out as a signal as an output of the comparator COM, and this disconnection detection signal is caught, and a frequency of an oscillation circuit B is changed by a frequency switching circuit E to alarm disconnection. By this, adjustment with high accuracy is made unnecessary, and disconnection can be detected with the simple constitution.</p> |
