Chamberlain Wireless Alert System

# International Electronics state-of-the-art wireless alert security system # Detects and reports human or vehicle motion # Only products with an effective transmission range from the sensor to the base for up to 1200 feet # Register a move up to 30 meters away # Works in temperatures from -40 º C (40 º F) to 100 º C (212 * F) # Resistant UV damage from sun # Special learning feature allows up to 4 sensor units to report to a single base station with unique sounds per sensor unit # Waterproof, includes a rain / sun shield # Conformal coated circuit is # Includes 10-amp outputs so it can be linked directly to a monitored system, a horn, lights,...

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Posted in: Alarm home system , alarm systems

Super Sensitive Intruder Alarm

Here is the circuit diagram of an ultra sensitive intruder alarm.The shadow of an intruder passing few meters nearby the circuit is enough to trigger the alarm. Here IC2 uA 741 is wired as a sensitive comparator ,whose set point is set by R6 &R7.The voltage divide by LDR and R9 is given at non inverting pin of IC2.At standby mode these two voltages are set equal by adjusting R9.Now the out put (pin6) of comparator will be high.Transistor Q1 will be off.The voltage at trigger pin of IC1 will be positive and there will be no alarm.When there is an intruder near the LDR the shadow causes its resistance to increase. [......

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Posted in: Alarm home system , alarm systems , electronic circuit

Window foil burglar alarm with scr

Here is a simple but effective burglar alarm circuit that can be fixed on windows to detect break throughs. The circuit uses a fine wire element fixed as a network through the window glass for sensing the break through . Normally the base of Q1 is held to ground potential by the wire element.So Q1 will be off and SCR H1 will not be conducting,and horn will be off.When the wire element is broken the base of Q1 will be raised to positive potential, Q1 will be on and so SCR H1 (TYN 612) will be ON making the horn to blow and this condition will be latched by the SCR.The circuit remains ON until the normal condition is restored or the power supply...

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Posted in: Alarm home system , alarm systems , electronic circuit

Night security light

Here is a simple circuit switches on a light around 2 hours after midnight, the time at which most of the robberies taking place. This simple circuit is build around a CMOS IC 4060 to obtain the required timing. During day time the LDR has low resistance and keeps the pin 12 of the IC1 high, preventing the IC1 from oscillating. When it is dark the LDR resistance becomes high and the pin 12 of IC1 becomes low and the IC starts oscillating, which indicated by the flashing of LED D3.The values of the timing components R1, R2, C4 are so selected that the out put pin3 of IC1 goes high after 8 hours. That means the high output drives the triac to...

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Posted in: Alarm home system , alarm systems , electronic circuit , Lighting