MASIGNCLEAN101

Ir Sensors (Infrared Leds) To Make An Object-Detection Circuit

There are various applications of IR sensors such as TV remote controllers, burglar alarms and
object counters. Here we have used IR sensors (infrared LEDs) to make an object-detection
circuit and also a proximity sensor for path-tracking robots. The basic idea is to transmit the
infrared light through an IR LED, which is then reflected by any obstacle ahead and sensed by the
receiving LED.

Another circuit

infrared (IR) remote controller comprises the transmitter and receiver sections. The range of the
transmitter can be increased up to 5 meter by using convex lens.

Circuit Description of infrared (IR) remote controller Transmitter section: – The transmitter circuit of infrared (IR) remote controller is built around IC
741 (IC1) wired as frequency square wave oscillator. Gate pulse from pin no 6 of IC1 is given to
gate of SCR1 to drive IR LED1. Variable resistor VR1 is used to vary the generated frequencies.
Receiver Section: – The receiver circuit of infrared (IR) remote controller consist an IC 741,
photo transistor (T1) and medium power transistor (T2).
Photo transistor receives the transmitted signal and given to pin 2 of IC2 for amplification. The
amplified output from pin 6 of IC2 is given to base of relay driver transistor (T2) through nonpolarized
capacitor C5, diode D1 and resistor R8. Variable resistor VR1 is used to match the
transmitting and receiving signal.

PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)
R1,R2 = 100 KΩ; R3, R5, R8 = 1 KΩ; R4 = 15 Ω; R6 = 22 KΩ; R7 = 10 MΩ; VR1 = 1 MΩ;
VR2 = 2.2 MΩ
Capacitors
C1, C3, C4 = 0.1 μF; C2 = 1 μF/100V; C5 = 2.2 μF/16V
Semiconductors
IC1, IC2 = 741; SCR1 = SN050; T1 = photo transistor; T2 = SL100; D1, D2 = 1N4001
Miscellaneous

RL1 = 15V, 500Ω Relay; IR LED
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