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Automatic Arming Auto Alarm

2016-02-18 23:01  
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When the car is turned off when the circuit opens automatically. It not only gives you a variable time to go out and locked up, but also provides a variable delay time and start the car. When the car is running, 555 oscillator / timer is always off, which makes the alarm is released. As long as the car is turned off, Q2 off and shunt UL certified power. When the car flameout, UL immediately its output high, keeping the third quarter, thus preventing the power back to U2. Transmission power collector of transistor Q2 Q3 UL only when the timer has completed its cycle. When completed Siniora proved, which in turn activates Q4 Q3 turns off, and the transmission power balance circuit. Timing cycle time required to get the car.

Automatic Arming Auto Alarm 
 

 LED1  indicates that the system is disarmed and LED2 indicates that the system is armed. At this point, U2 waits for a trigger pulse from the car`s door switches or dome light. A positive impulse at the 401 l`s input sends a negative trigger pulse to the first stages of U2, which is connected as a cascading timer. The first stage`s output becomes high for a time to allow the car to be turned on. If that does not happen, the first stage`s output lowers, which sends a low trigger pulse to the second stage. The second stage then sends its output high, turning on Q5, which sounds the alarm for a given time. Once that time has elapsed, the alarm is shut off by a low output to Q5 and the system is reset. If the car door is closed or a second door opened while the alarm is sounding, the first stage retriggers and prepares to extend the ON-time of the alarm. The cascading or counting action continues until the car is left alone. You can add a switch on the positive supply rail at J3 to override and silence the alarm, if (for example) you plan to work on the car. Switch SI is a normally closed type that is built into the case of the alarm; SI is pushed to the open position when the case is mounted flush with a surface. Any attempt to remove the alarm will sound the alarm.
 

 



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