Having a reliable, high-quality alarm intruder system is one of the best ways you can protect your property and the people who live and/or work there. Regardless of how big or small your property is making sure that all points of entries (not just doors and windows) are secure is a crucial undertaking. The second tier receives the information and sets off an alarm which alerts the authorities, either silently or a loud internal warning alarm. Once it detects something, it sends the information to the second line of defense. The system acts as your digital eyes and ears detecting intruders and other signs of suspicious activity. Security intrusion detection provides you with two layers of defense. ( What Is An Intrusion System) Intrusion alarm systems: how does it work? After all, safety, which includes personal and property security, is one of the most basic needs of human beings according to Abraham Maslow’s Hierarchy of Needs. If you are considering installing an intruder alarm to protect your home and/or business, then you are doing the right thing. Loss prevention for large & Small business Restaurants & Small Coffee Shops Surveillance.Contact for Advice & Schedule Consultation.You can also increase the sensitivity by the variable resistor VR1. It is recommended that keep LDR inside black tube or pipe to increase the sensitivity of LDR. This will trigger the IC2 and the alarm or buzzer connected to it will start sounding. The output pin 6 of IC1 become low causing the transistor T1 to conduct. Now as person enters its shadow will fall on LDR because of change in light intensity on LDR voltage at non inverting input pin 3 will become low.
Because if this IC2 will not oscillate and alarm will remain off. Initially when nobody is present in front of sensor (LDR), output pin 6 of IC1 is at high voltage level which makes the base of transistor T1 also high and its emitter is also high that’s why at this time transistor T1 will not conduct. LDR and variable resistor VR1 is used to provide variable voltage input at non inverting terminal pin 3. We have used resistor R1 and R2 to provide half supply voltage at inverting terminal. In this circuit we have made a two potential divider circuit one at inverting terminal (pin2) and another at non inverting terminal (pin 3) of IC1. LDR, Preset VR1 which provides reference voltage to the non-inverting terminal pin 3 and LDR and R1 and R2 is connected to inverting pin 2 of IC1 and few more components. In mono-stable mode IC is once trigged, it will hold the output for a specific interval of time as defined by the timing component before returning to its original state and we are utilizing this property in our circuit. ?A741 is used as a sensitive voltage comparator, NE555 wired in mono-stable mode.
The circuit comprises of Operational amplifier. It can be used as fence alarm to protect your garden from animals.You can also use it at your doors to indicate that some stranger is present on door. Circuit will give you loud alarm enough to detect the presence of person in restricted area. The circuit described here is very sensitive and it can detect the moving person at a distance of few meters and we do not require much alignment. Various types of alarms are available in market to protect the entry of unauthorized person in restricted area but they require precise alignment.
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