Circuit Diagram
Description
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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