How To Construct Light Alarm System

his project provides the schematic and the parts list needed to construct a simple Light Alarm. Protect your medicine cabinet, cash drawer or lolly cupboard with this alarm. It will sound as soon as the drawer is opened and light falls on the Darlington phototransistor. It may be connected remotely at the end of two pieces of wire. The output alarm may be redesigned to activate a relay or triac.
The project is a light alarm which will detect very low levels of light. It will not work as well as your eye in detecting light because the human eye is the most sensitive light detector there is. But it comes close. For best results have the MAL12 pointed in the direction which light will come.

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Filed Under: LED, Security

5 Zone Alarm System

This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC's and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system armed" indicator.

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Filed Under: Security

Anti-Theft Security For Car Audios

This is based on popular CMOS NAND chip CD4093,can be effectively used for protecting your expensive car audio system against theft.
When 12V DC from the car battery is applied to the gadget (as indicated by LED1) through switch S1, the circuit goes into standby mode. LED inside optocoupler IC1 is lit as its cathode terminal is grounded via the car audio (amplifier) body. As a result, the output at pin 3 of gate N1 goes low and disables the rest of the circuit.

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Filed Under: Security

Security System Switcher

An audio signal can be used as a form of input to control any security system. For example,an automatic security camera can be configured to respond to a knock on the door. The circuit described here allows the security system to automatically switch on when a master switch is in on state. It uses a transducer to detect intruders and a 5V regulated DC power supply provides power to the circuit.

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Filed Under: Security

Touch Switch And Delay Circuit

Circuit Description:

This is a simple touch switch circuit,the 555 timer is configured as a one shot multivibrator that is triggered by touching the touch terminal. In this monostable mode, the timer generates a fixed pulse of about 4 seconds whenever the trigger voltage falls below Vcc/3. When the trigger pulse voltage applied to the #2 pin falls below Vcc/3 while the timer output is low, the timer's internal flip-flop turns the discharging Tr. off and causes the timer output to become high by charging the external capacitor C2 and setting the flip-flop output at the same time.

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Filed Under: hobby project, Security

Automatic Room light Control With Bi Directional Visitor Counter

The objective of this project is to make a controller based model to count number of persons visiting particular room and accordingly light up the room. Here we can use sensor and can know present number of persons.In today’s world, there is a continuous need for automatic appliances with the increase in standard of living, there is a sense of urgency for developing circuits that would ease the complexity of life.

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Filed Under: hobby project, Security

Touch Alarm System

Touch Alarm circuit is widely used for security, which is installed on the door. The advantages of this alarm is cheap and difficult to detect by burglars / intruders.The following is an example of a touch of alarm circuit which is designed by Tony Van Roon.

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Filed Under: Security

PIC Security System Dials Your Cell Phone

This is a Do-it-yourself phone dialer security system calls your cell phone, office etc.whenever a door or window is opened,or panic button is pressed. The circuit consists of a small PIC microcontroller, assembly program, and a few other parts to detect a switch closure from an open door, window,or manual push button and then dial the cell phone number,and transmit a steady tone to indicate the source of the call. The circuit uses the pulse dialing system to interrupt the line connection a number of times to indicate each digit.Pulse dialing (the oldest form of dialing) works by actually disconnecting or "hanging up" the phone line a number of times to indicate each digit. For example, the digit "5" would be dialed by disconnecting and reconnecting the line 5 times in short intervals of about 100mS.There is about a 1 second pause (with the line connected) between each digit.The timing is not critical and I was able to dial 411 and connect to the local information service just using a momentary push button switch in series with the phone line.

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Filed Under: Security