Week : 6

Title : Circuit diagram of IR motion detector

Objectives : To know the connection of the component used in the circuit

Contents / Procedures :

Result / Analysis :

Here is the circuit diagram of an infrared motion detector that can be used to sense intrusions.Infra red rays reflected from a static object will be in one phase, and the rays reflected from a moving object will be in another phase.The circuit uses this principle to sense the motion. The IC1 (NE 555) is wired as an astable multivibrator .The IR diode connected at the output of this IC produces infrared beams of frequency 5Khz.These beams are picked by the photo transistor Q1 .At normal condition ie; when there is no intrusion the output pin (7) of IC2 will be low.When there is an intrusion the phase of the reflected waveforms has a difference in phase and this phase difference will be picked by the IC2.Now the pin 7 of the IC 2 goes high to indicate the intrusion.An LED or a buzzer can be connected at the output of the IC to indicate the intrusion.

Conclusion :

Comparators IC2a and IC2b are belonging to the same IC2 (LM1458).So the power supply is shown connected only once.When there is disturbance in the air or vehicles passing nearby,the circuit may get false triggered.POT R5 can be used for sensitivity adjustment.

 

Week : 5

Title : Concept of motion detector for security system

Objective : To know how infrared motion detector components work

Content / Procedure : 

 

Figure 1 : Infrared Motion Detectors

Result / Analysis :

Figure 1 above show the operation of an infrared motion detector for security system. In the system each sensor consists of two housings.One housing contains an infrared emitting diode and an infrared sensitive phototransistor as infrared detector. The other housing contains an infrared reflector to reflect the infrared signal.When positioned in front of an entrance to a protected area, the two housing establish an invisible beam as shown in figure 2 below:

Figure 2 : The concept of infrared motion detector for security system

Conclusion :

A person who enters the area will interrupts the beam causing an alarm to be trigerred. For this type of motion detector use the basic concept of the infrared motion detector.An interruption in the signal modulated pulsating beam transmit by an infrared diode while receive by an infared detector that will set 'on' or 'off ' the alarm of the security system