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Single CMOS alarm circuit

2016-02-21 20:37  
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The article describes a single CMOS alarm circuit. The circuit is very simple, very helpful. If you understand this principle is not very thorough, it is recommended to understand some of the important components of the circuit. This circuit features automatic Exit / input delay, timed bell cut-off and the system is reset. It provides a normally open, normally closed switch that will satisfy the usual input devices, such as aluminum foil tape, pressure pads, magnetic reed contacts, passive infrared detectors and inertia (shock) sensor. Green Led lighting should be set before the police. When you open SW1 red Led will light exit delay will begin. You have about 30-40 seconds to leave the building. Buzzer will sound like you. It should stop sounding when you shut the door behind him, indicating that the trigger circuit has been successfully restored within the time allowed. In return, when you open the door  buzzer  will sound. Then you have about 30-40 seconds SW1 moves to the "OFF" position. If you fail, the alarm sounds. About 15 - 20 minutes later, when the relay drops out, the alarm will attempt to reset the switch itself through the use of a third "off" briefly. If the trigger circuit has been restored alarm will reset. If not, the attempt will fail and the alarm will be re-activated. It will continue to attempt to reset itself every 15 to 20 minutes until the trigger circuit is restored; or alarm off. Exit delay, and Bell entry deadline can be changed by changing the value of R8 & R11 R12, respectively. Inertial sensor sensitivity adjustment R4. Set to the minimum, tap will activate the alarm. Set to the maximum, you need a heavy blow. If you are not using inertial sensors and replace R4 and 220 k fixed resistor. If you do not use normally open switch and then left R1, C1 and Q1 and adaptation between the green Led and C2. The next stage is appropriate resistor, most of the diode, IC sockets. Use a socket to reduce the possibility of damage IC; and make it easier to replace if necessary. Resistance are shown to lie down on the board. However, the connection is closed or installed between adjacent tracks to walk upright, like some diodes. Finally, with the remaining components (capacitors, transistors, diodes, relays); Add 10 solder bridge at the bottom of the board; complete the insertion Cmos 4081 to the socket. 



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