Published:2011/4/28 18:52:00 Author:Christina | Keyword: Car coolant, alarm circuit | From:SeekIC
The car coolant alarm circuit is as shown in the figure. If the coolant level is normal, the sensor is grounded through the liquid, in the figure, a point has no voltage level. When switch turns on, level alarm system will check itself. Specific work process is as follows:
(1)Turn on the ignition switch, the main relay starts working. c1 is charged by the high charge current and this current maintains the t1 turns on, t2 turns on, t3 turns on, then the indicator turns on.
(2)When the c1 is full, current is gradually reduced, t1 turns off, t2 turns off, t3 turns off, then the indicator turns off.
The light-time is related with the parameters c1. When this device is checking itself, if the warning light does not shine, it means there is something wrong with the alarm system, you should check it.
(3)If the liquid level is too low, the sensor can not reach the liquid, Point a's voltage level becomes higher, t1 base potential becomes higher too, t1 turns on, t2 turns on, t3 turns on, then the indicator turns on, When this device is checking itself, if the warning light does not turns off, it means the coolant liquid level is too low, you need to fill it.
(4)When the coolant level is normal, if you turn off the switch, c1's charge-circuit is: c1(+)→r1→r11→r10→c1(-).
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