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.
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
|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|