1. Wireless Home Security System<br />Introduction<br />Wireless home security systems are the modern day choice for home protection. Security systems are valuable tools in protecting against many of the dangers that can happen in and around a home. Systems safeguard homes from intruders, burglars, and fire damage. In some cases, security systems can be set to alert in case of a freeze or a flood as well.<br />Home security begins with home safety. Home safety begins with homeowners taking steps to protect their home, its contents, and its residents. One of the best ways for homeowners to have a safe home is to install a security system. Security systems can be wired or wireless. However, wireless systems are arguably the most easy to use and the simplest to install.<br />Wireless home security systems can be purchased from many stores and companies. Some of these companies will send an installer to a residence to install a system. Other companies sell kits that a homeowner will need to install on their own. A few of the most popular security companies are Honeywell, ADT, Brinks, and different local security companies in different areas of the country. Each company has their own systems and their own packages for sale. Choosing the right company and system depends on a home’s needs and structure as well as your own budget for the project.<br />Security systems that are wireless usually include cameras, alarm sounders, motion detectors, and other installation items. These items are the components that make up the entirety of a home security system, and each of these items has a function and a purpose that helps to protect a building or a piece of property.<br />Cameras are an important item in wireless home security. Cameras are convenient to use to monitor anything that a property owner deems important to keep an eye on. They can be mounted anywhere that sits within the signal range of the wireless transmitter. Also, most alarm systems are able to instantly record any video footage onto a local computer hard drive. This allows easy access to footage 24-hours-a-day.<br />Alarms are another common aspect of a security system. Alarms are used to startle thieves and alert the proper authorities that a building is being victimized. Alarms can sound for many reasons. Some of these reasons include an intruder, a fire, a freeze, or a broken window or door.<br />Wireless home security systems will also often used motion detectors and sensors. These are frequently placed in areas of a building that are not accessed often. In these spaces that are not commonly traveled, sensors can alert homeowners to movements that may be from burglars or other intruders.<br />Wireless home security systems are frequently monitored by the companies that manufacture them. This is often 24-hour monitoring. This means that homeowners will usually be able to call for help with a simple touch of a button, and company employees can call a homeowner if the alarm is sounding for a fire, freeze, flood, or intruder, which will ensure their safety.<br />Block Diagram<br />home security System<br />Securiy is a matter of great concern to all of us in this world. Normally there are four types of security threat to our property. 1 )Thief, an inturder. 2)Fire, so we use fire sensor. 3)Water spilage /over flow, so we use water sensor. 4) Gas leak , we use gas sensor, whenever there is security breach from one of above or any combination of above. The project takes the following action 1) Sounds an ALARM to attract your home Security project <br />or public attention . 2) If the reset sw is not pressed within 30 seconds the projects takes further action, 3) It makes an emergency call to deliver an emergency message stored in speech IC. 4) It will make five attempts to call you before it checks the conditions again. The project presented here is based on world’ s most powerful intel’ s mcs-51 family of microcontroller atmel at89c51. CIRCUIT EXPLANATION: This project is based on 8051 microcontroller.(IC2) IC3 and is used as buffer. IC4 is a one time programmable(otp) chip where messages are stored. This is 21 second speech ic where total of 12 messages can be recorded on eight different locations, but total duration should not be more than 21 seconds. Recorded messages can be played back by setting the trigger pin 10 & 11 to high, making these pin low will stop the message, Setting these pin high will repeatedly replay the same message. IC5 is an audio amplifire . Audio output from speech ic(IC4) pin no 7 cout is coupled to this ic on pin no 3 through VR2 volume control and C10. Amplified output from pin no 5 drives the speaker through capacitor C14. R14 and C13 corrects the tone. .C15 and C16 couples the audio message to telephone line. IC4 needs 3.3v operating voltage .R9 is a voltage dropping resistor, D7 is 3.3v zener diode and C7 is a filter capacitor. These components will always maintain the voltage to3.3v at pin 9,12 of IC4. capacitor C8 is a feed back capacitor.,C9 and R13 connected to pin no 7 of IC 4 are tone corrector.R12 along with the VR1 variable resistor performs the sampling rate adjustment. R10 and R11 connected to pin26 and pin 27 of the microcontroller are voltage dropping resistors. R15 and R16 connected to the base of transister Q1 and Q2 are voltage dropping resistors and drives transistors Q1 & Q2 when set to high logic by microcontroller. Q1 Drives the dial relay RL1and Q2 drives the off-hook relay<br />