How Infrared Sensors Work?

Remote operation of TV is based on Infrared transmission and reception. Infrared is a form invisible light with a wavelength of 950 nano meters. Human eye cannot sense this wavelength so that infrared rays cannot be detected visually. The remote handset is used to emit modulated infrared light using an infrared diode. This diode emits pulsed infrared waves in a coded form at a frequency of 38 kHz By pressing each button in the remote handset, it is possible to emit infrared rays at a particular coded form. This helps to control the functions of the TV precisely. Inside the TV there is an Infrared receiver circuit. It consists of an infrared sensor- TSOP 1738. This sensor is sensitive only to pulsed infrared rays at the 38 kHz frequency and not other forms of light. The infrared sensor has a black covering which filter visible light and allow only the infrared to enter. It has an FET bas signal amplifier. The modulated infrared rays from the handset are received by the sensor and it amplifies the signal. These signals are used for controlling different functions of the TV.

1 2 3GN VCC OUT

TSOP1738

Type Pin 1 Pin 2 Pin 3 Type Pin 1 Pin 2 Pin 3 TK 1836 OP GN VCC SHARP GPIU

561X VCC OP GN

SFH 5110-38 OP GN VCC TK 19931 GN VCC OP SFH 505A VCC GN OP ISIV 60 OP GN VCC TK 19-904 GN VCC OP ISIU 60 OP GN VCC TSOP 1738, GN VCC OP TSOP 1736 GN VCC OP SFH 506-38 GN VCC OP TSOP 1838 GN VCC OP Pin numbers 1, 2, 3 assigned from the facing side Infrared Sensors require 5volt maximum. Do not give more than 5 volt Vcc