Notes 4 The Project

Motion Detector By Infrared In General the project all about 4 sections which are: 1.Power Supply 2.IR Detector 3.Filtering operations by op. amp. 4.And The Tone Generator "it's main use is in the alarm systems ". "Power Supply": The voltage of the circuit comes from 9v battery (DC) we can Regulate the voltage by a Circuit called "voltage Regulator" "The IR Device": form of radiated energy in which the wavelength is longer than the wavelength of the visible light. if the wavelength goes up, then the freq. goes dowen and v. v. the wavelength of the IR light ranges from 78 micrometers to100 "the micrometer = 1,000,000 meter". it contain 2 crystals connected with each other in opposite polarity(+- ; -+), 1 mm optical space. there location is behind an optical filter or lens. the o/p power of the crystal is very low so we use the "FET" Transistor "Field Effect Transistor" to increase the o/p power.. *How we use it physicaly: the crystals produce a voltage at the gate of the FET, this will causes a change in Current from Drain to source. very little power is required at the Gate to control the larger Current flow from source to drain. *How we use it in our circuit: it contain a few components such as "R1 ,R2 ,C1 and the PIR sensor". now as motion is detected the IR detector will produce a voltage at the gate of the FET, allowing current to flow from drain to source. so the voltage at the i/p of U1 pin 13 will change, this changing the o/p at pin 14. R1 and R2 limit the amount of current flow through the FET... the Benefits of this type: 1.low radio interference 2.low noise 3.The IR detector is sealed in a metal housing to prevent electromagnetic interference and to keep them clean. NoTes: -When certain materials change temperature, they produce electricity. if a pyroelectric crystal doesn't change it's temp. for a while then no voltage will across it's electrodes, but when it's temp. changes a voltage will produced at the electrodes of it's crystal "this hole idea is used in the IR Detector". -the most important specification neede in choosing a motion detector is the max. distance and total angle of view. -"Operations by op. amp.":

A. The meaning of the amplifire is a device that uses a "small amount of power to control a larger amount of power". B. The amplifier does not create power but it controls the power from a source. -The Op Amp: the characteristics of an ideal op-amp are the following: 1.infinite voltage gain (no v in i/p, larg v on o/p) 2.infinite bandwidth (no matter how fast the i/p changes, o/p changes as fast) 3.infinite input impedance (no need power in i/p to change o/p) 4.zero output impedance (o/p can deliver infinite power) the op-amp can be used to compare the amplitude of one voltage with another it is used without feedback and at maximum gain -FILTERS LOW AND HIGH PASS FILTER'S: 1.The Low pass decreases all signals above a certain frequency and passes frequencies below that freq. 2.The High pass decreases all signals below a certain frequency and passes frequencies above that freq. -The Pand Bass Filter: we can recognize a Pand Bass filter by the compnition between low and high CIRCUIT DESCRIPTION: The op-amp IC1D shapes the frequency response to amplify those frequencies produced when motion is detected and rejects all others, such as those due to noise or slow temperature changes. Frequencies above 20Hz and below 1Hz are beyond the bandwidth of the circuit and thus are rejected. The output at pin 14 is about 1.6V when no motion is detected. As motion is detected, the voltage at the output will change and trigger either IC1C or IC1B. The op-amps IC1A, IC1B and IC1C are configured as voltage comparators. In the ready state, the output of IC1A is high and IC1B and IC1C are low. When IC1D outputs a voltage lower than 1.41V, it will force pin 2 of IC1 high. When IC1D outputs a voltage higher than 1.67V, it forces pin 8 and pin 2 of IC1 to go high. A high in with one of these cases causes the output to go low and allows C9 to discharge through IC1A. The discharging of C9 will pull pin 6 of IC2 low and trigger the sound generator.

the C6 (100 mf): to filter or made it smooth the o/p Voltage