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 non- polarized 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
