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infrared beam break detector circuit

Infrared Beam Break Detector

Application

An infrared detector that sounds a buzzer when an IR beam is broken, meaning the IR signal is lost. A pulsed IR signal generator is necessary, but not included in this post. This project would be ideal for doorways or hallways to alert when someone enters or exits an area.

Description

The IR sensor responds to pulsed infrared, not ambient or continuous IR. This means that another transmitter project is necessary in order to complete this one! Note though that some forms of lighting like fluorescent lighting may interfere with the sensor. For convenience, the the buzzer is internally driven so that a only Vdc is needed to make a sound. In this case, the IR sensor senses 38kHz pulsed infrared light.

Pin 3 of the IR sensor is actually low (0V) while receiving a signal. When the sensor is blocked from receiving the IR signal, the sensor outputs a high signal to the comparator, which then allows current through the LED/Buzzer circuit, and alerting you that the beam is broken. In the Scheme-It drawing the LM311 IC is a grouping of three components, in a functional block diagram style, to show how it functions in the circuit beyond what the pinouts would show normally.

Schematic of the IR Beam Detector Circuit

infrared beam break detector circuit

Parts list

RefDes

Name Value Part Number Digi-Key Part Description
U1 IR SENSOR GP1UX511QS 425-2501-ND RECEIVER IR REM CTRL 5V 38KHZ
R1 RESISTOR 22K

ERJ-8GEYJ223V P22KECT-ND RES 22K OHM 1/4W 5% 1206 SMD
R2 RESISTOR 1K ERJ-8GEYJ102V P1.0KECT-ND RES 1K OHM 1/4W 5% 1206 SMD
C1 POLARIZED 10uF 293D106X0025C2TE3 718-1044-1-ND CAP TANT 10UF 25V 20% 2312
U2 OPAMP LM311 LM311DR 296-1388-1-ND IC DIFF COMP STROBE 8-SOIC
R3 RESISTOR 1K ERJ-8GEYJ102V P1.0KECT-ND RES 1K OHM 1/4W 5% 1206 SMD
L1 LED TLHK5800 751-1119-ND LED 5MM RED 5500MCD ALINGAP GAAS
SPK1 SPEAKER Buzzer CT-1205CL-SMT 102-1267-1-ND BUZZER AUDIO MAGNETIC 5VDC SMD

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