Components Used in the Project

• (D1) IR transmitter LED *1
• TL1838 Infrared Receiver *1
• (U1-2) NE555 SOP8 *2
• (R3-7) 0805 470 Ohm *2
• (R4) 0805 470 KOhm *1
• (R5) 0805 10 Ohm *1
• (R1) 0805 10 KOhm *1
• (R6) 0805 220 Ohm *1
• (R2) 0805 1.8 KOhm *1
• (C1,2,3,4,8) 0805 10nf *5
• (C7) 150uf 16v *1
• (C5) 4.7uf 10v *1
• (C6) 1uf 10v *1
• (Q1) D882 SOT-89-3L *1
• (Q2) TIP32C TO-220 *1
• (P1) WJ124-3.81-4P *1

Description

This infrared proximity detector using an infrared detector. can be used in various equipment like automatic door openers and burglar alarms. The circuit primarily consists of an infrared transmitter and an infrared receiver. I made this project for hand sanitizer devices when the COVID-19 pandemic started. I tried many other projects were unsuccessful until I built this project. For example, some of them were self-study, influenced by the sun. The transmitter section consists of a 555 timer IC functioning in astable mode. The output from astable is fed to an infrared LED via resistor R5, which limits its operating current. This circuit provides a frequency output of 38 kHz at 50 per cent duty cycle, which is required for the infrared detector/receiver module. TL1838 Infrared Receiver is turned on by a continuous frequency of 38 kHz with 50 per cent duty cycle, requires a burst frequency of 38k to sense. Hence, TL1838 Infrared Receiver is used. The receiver section comprises an infrared receiver module, a 555 monostable multivibrator, and an LED indicator. Upon reception of infrared signals, 555 timer (mono) turns on and remains on as long as infrared signals are received. When the signals are interrupted, the mono goes off after a few seconds (period=1.1 R4xC6) depending upon the value of R4-C6 combination. Thus the mono period will be around 1 seconds. Both the transmitter and the receiver parts can be mounted on a single breadboard or PCB. The infrared receiver must be placed behind the infrared LED to avoid false indication due to infrared leakage or should be limited to a heat tube makaron. An object moving nearby actually reflects the infrared rays emitted by the infrared LED. The infrared receiver has sensitivity angle (lobe) of 0-60 degrees, hence when the reflected IR ray is sensed, the mono in the receiver part is triggered. The output from the mono may be used in any desired fashion. For example, it can be used to turn on a light when a person comes nearby by energising a relay. The light would automatically turn off after some time as the person moves away and the mono pulse period is over. And finally, I want to say what I think about this competition. I have never participated in such a competition and I have never heard of a company that does such a competition. This is a great idea and I think it will inspire people, so congratulations to the allpcb team. I wish success to all my participating friends.