This infrared object counter can be installed on the entrance door to count the total number of people entering anywhere. For example, it can be used at train stations or bus stops to count people arriving by day or week.
The meter uses an infrared transceiver pair and a simple, low-cost calculator. It works even in the presence of normal light. The maximum detection range is approximately 10 meters. This means that the transmitter and receiver must be installed (on the opposite pillars of the door) at a distance of not more than 10 meters. No focusing lens is required. If an 8-digit calculator is used, the counter can easily count up to 99,999,999, and if a 10-digit calculator is used, the counter can count up to 9,999,999,999.
Infrared object counter Circuit
Powered by a 9V battery, the transmitter circuit (see Fig. 1) comprises IC 555 (IC 1), which is connected as an astable multivibrator with a center frequency of approximately 38 kHz, and two infrared (LED) light emitting diodes . The receiver circuit (see Fig. 2) is powered by a 5V regulated power supply built around transformer X1, rectifier bridge comprising diodes D1 to D4 and regulator IC2. It uses an infrared receiver (IR) module (RX1), optocoupler (IC3) and a simple calculator.
Circuit operation
When switch S1 is in the "on" position, the transmitter circuit is activated to produce a square wave on its output pin 3. The two infrared LEDs (IR LED1 and IR LED2) connected at their output transmit modulated IR beams at the same frequency (38 kHz). The oscillator frequency can be adjusted using the preset VR1.
In the receiver circuit, the TSOP1738 IR receiver module, commonly used in color televisions, is used as the sensor to detect the IR signals transmitted from the television remote control.
The IR-transmitted IR beams LED1 and LED2 fall into the IR receiver module RX1 of the receiver circuit to produce a low output level at its pin 2. This keeps the transistor T1 in the unmanned mode.
Now when someone enters the gate to interrupt the IR beam, the IR receiver module produces a high output pulse on its pin 3. As a result, transistor T1 leads to activate IC3 and its internal transistor sets the '=' key of the calculator to advance the count by one.