| 摘要 |
PURPOSE:To prevent a temperature rise of a solenoid, and also to make the solenoid small-sized by controlling a driving time of the solenoid basing on signal corresponding to a power supply voltage. CONSTITUTION:When a magnet disk 1 rotates as an automobile runs, a control part 3 processes a signal generated from a reed switch 2 and generates a distance pulse. In this case, if a battery voltage is under 10V, both comparators 4f, 4g send out a signal of ''0'' level, and a signal continuous time of the distance pulse becomes the longest. Also, when the battery voltage is above 10V and under 14V, an output of the comparator 4g becomes ''1'' level, the signal continuous time of the distance pulse becomes short, and when the battery voltage becomes above 14V, both the comparators 4f, 4g become ''1'' level, and the signal continuous time of the distance pulse becomes shorter. Accordingly, an electric energy supplied to a solenoid 7 becomes roughly constant.
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