10-02-2012, 03:40 PM
Infrared Object Counter
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This infrared object counter can
be installed at the entry gate to
count the total number of people
entering any venue. For example, it can
be used at the railway stations or bus
stands to count the people arriving per
day or week.
The counter uses an infrared transmitter-
receiver pair and a simple, lowcost
calculator. It works even in the
presence of normal light. The maximum
detection range is about 10 metres. That
means the transmitter and the receiver
are to be installed (at the opposite pillars
of the gate) not more than 10 metres
apart. No focusing lens is required. If an
8-digit calculator is used the counter can
count up to 99,999,999 easily, and if a
10-digit calculator is used the counter
can count up to 9,999,999,999.
Powered by a 9V battery, the transmitter
circuit (see Fig. 1) comprises IC
555 (IC1), which is wired as an astable
multivibrator with a centre frequency
Rambir Singh of about 38 kHz, and two infrared
light-emitting diodes (LEDs). The
receiver circuit (see Fig. 2) is powered
by a 5V regulated power supply built
around transformer X1, bridge rectifier
comprising diodes D1 through D4
and regulator IC2. It uses an infrared
receiver (IR) module (RX1), optocoupler
(IC3) and a simple calculator
