The circuit may be used to automatically switch on a light at the entrance gate to the premises at night by sensing the presence of a person. In addition, it sounds an alarm to signify the presence of a person. Here we are using an IR Led as the transmitting unit and the TSOP as receiving unit. A monostable, multivibrator circuit is used for the purpose of getting time delay accordingly. Lamp is switched on only for a short interval to save electricity. The main application is its use in restricted areas to indicate the entry of trespassers. It can also be used for security purposes. 

MOTIVATION

In the present busy world cases may arise where we may not be able to keep a constant watch in certain areas. In such cases arises the application of our project. This actually serves as a detecting mechanism to indicate the presence of an object or person in undetected cases. This turned out to be our main motivation for us to do this project.

The necessity to find a solution of all these problems turned out to be the motivation; also we have succeeded in overcoming these difficulties by implementing this project.

This circuit has two stages: Transmitting unit and receiving unit. Transmitting unit consists of IR LED and sensing unit consists of TSOP sensor. An IC 555 working in monostable mode gives the time delay. The circuit may be used to automatically switch on a light at the entrance gate to the premises at night by sensing the presence of a person.

In addition, it sounds an alarm to signify the presence of a person. Here we are using an IR Led as the transmitting unit and the TSOP as receiving unit. A monostable, multivibrator circuit is used for the purpose of getting time delay accordingly. Monostable multivibrator often called a one shot multivibrator is a pulse generating circuit in which the duration of this pulse is determined by the RC network connected externally to the 555 timer. In a stable or standby state, the output of the circuit is approximately zero or a logic-low level. When external trigger pulse is applied output is forced