This circuit can be used to protect your valuable documents and jewellery from theft or intruder. Just put the switch under the mat or in front of locker so that when unauthorised person come it will walk over the switch and this will trigger the circuit and alarm start sounding. Main advantage of this circuit is you can use it in two places because both switches produce different sounds.In this circuit two switches S1 and S2 are used for two places like one can be used on front door and another can be used in front of locker. When S1 is pressed diode D1 connected to it start conducting because of that transistor T1 and T2 connected through resistor start conducting. Capacitor C1 is used to provide positive feedback to transistor T1 and T2 for oscillation. When S1 is pressed low frequency tone is generated indicating that intruder is present on door.
In current times, it is necessary to have some security at home. To avoid acts of vandalism and thefts, we need instant responsive security alarms that are active [[wysiwyg_imageupload::]]all the time. This circuit is very helpful at this situation. We have a smart security alarm which can be used in home, in your locker or in cash box guard that thwarts the theft attempt by activating an emergency alarm.The circuit is built around the CD4060 and few more components. IC CD4060 is 14 stage ripple carry binary counter, divider and an oscillator. Its built in oscillator is main feature of this IC that’s why it can be used in numerous application like flasher, clock generator in timer circuits.Read more to find out working of the circuit with the help of circuit diagram, description and detailed information about the components used.
The circuit gives an audio visual alarm when somebody enters from a door. This project can also be used in locker and almirah door. This circuit is based on [[wysiwyg_imageupload::]]operational amplifier LM741 and LDR. An op-amp produces an output voltage that is hundreds of thousands times larger than the voltage difference between its input terminals. The circuit comprises of Operational amplifier A741 which is used as sensitive voltage comparator, LDR and Preset VR1. The preset provides reference voltage to the non-inverting terminal pin 3 and LDR. R2 is connected to inverting pin 2 of IC1. How does the alarm sense someone entering? How is the circuit constructed? What is the role of op-amp in its working? Continue reading to find out how answers to these questions and more.