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Here
is a handy gadget for test- ing of infrared (IR) based re- mote
control transmitters used for TVs and VCRs etc. The IR signals
from a remote control transmitter are sensed by the IR sensor
module in the tester and its output at pin 2 goes low. This in
turn switches on transistor T1 and causes LED1 to blink. At the
same time, the buzzer beeps at the same rate as the incoming
signals from the remote control transmitter. The pressing of
different buttons on the remote control will result in different
pulse rates which would change the rate at which the LED blinks or
the buzzer beeps. When no signal is sensed by the sensor module,
output pin 2 of the sensor goes high and, as a result, transistor
T1 switches off and hence LED1 and buzzer BZ1 go off. This circuit
requires 5V regulated power supply which can be obtained from 9V
eliminator and connected to the circuit through a jack. Capacitor
C1 smoothes DC input while capacitor C2 suppresses any sudden
spikes appearing in the input supply. Here, a plastic moulded
sensor has been used so that it can easily stick out from a cut in
the metal box in which it is housed. It requires less space.
Proper grounding of the metal case will ensure that the
electromagnetic emissions which are produced by tube-lights and
electronic ballasts etc (which lie within the bandwidth of
receiver circuit) are effectively grounded and do not interfere
with the functioning of the circuit. The proposed layout of the
box containing the circuit is shown in the figure. The 9-volt DC
supply from the eliminator can be fed into the jack using a
banana-type plug.
Tech. Editor’s note: In fact, the complete gadget can be assembled
in the eliminator’s housing itself and a cut can be made in its
body for exposing the IR module’s sensor part.
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