In today’s world, there is a
continuous need for automatic appliances with the increase in standard of living;
there is a sense of urgency for developing circuits that would ease the
complexity of life.Infrared interruption counter is a reliable circuit
that takes over the task of counting number of interruptions very accurately.
When somebody enters into the room, then the Counter is Incremented by one. The
total number of Persons inside the Room is displayed on the seven segment
displays. The microcontroller does the above job it receives the signals from
the sensors, and this signals operated under the control of software which is
stored in ROM.
The microcontroller receives the
signals from the sensors, and this signal is operated under the control of
software which is stored in ROM. Microcontroller AT89C2051 continuously monitor
the Infrared Receivers, When any object pass through the IR Receiver's then the
IR Rays falling on the receiver are obstructed , this obstruction is sensed by
the Microcontroller. The buzzer will produce beep sound on every interruption.
Block diagram
Transmission
circuit
This circuit diagram shows how a 555 timer IC
is configured to function as a basic monostable multivibrator. A monostable multivibrator is a timing
circuit that changes state once triggered, but returns to its original state
after a certain time delay. It got its
name from the fact that only one of its output states is stable. It is also known as a 'one-shot'.
In this circuit, a negative pulse applied at pin 2
triggers an internal flip-flop that turns off pin 7's discharge transistor,
allowing C1 to charge up through R1. At the same time, the flip-flop brings the
output (pin 3) level to 'high'. When
capacitor C1 as charged up to about 2/3 Vcc, the flip-flop is triggered once
again, this time making the pin 3 output 'low' and turning on pin 7's discharge
transistor, which discharges C1 to ground. This circuit, in effect, produces a
pulse at pin 3 whose width t is just the product of R1 and C1, i.e., t=R1C1.
Receiver
circuit
The IR transmitter will
emit modulated 38 kHz IR signal and at the receiver we use TSOP1738 (Infrared
Sensor). The output goes high when the there is an interruption and it return
back to low after the time period determined by the capacitor and resistor in
the circuit. I.e. around 1 second. CL100 is to trigger the IC555 which is
configured as monostable multivibrator. Input is given to the Port 1 of the
microcontroller. Port 0 is used for the 7-Segment display purpose.
List
of components
Microcontroller – AT89C2051
IC – 7805
Sensor – TSOP 1738 (Infrared Sensor)
Transformer – 12-0-12, 500 mA
Preset – 4.7K
Disc capacitor – 104,33pF
Reset button switch
Rectifier diode – IN4148
Transistor – BC 547, CL 100
7-Segment Display
Flow chart description
If the sensor 1 is interrupted first then the
microcontroller will look for the sensor 2.And if it is interrupted then the
microcontroller will increment the count
If the sensor 2 is interrupted first
then the microcontroller will look for the sensor 1. And if it is interrupted
then the microcontroller will decrement the count.
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