20-05-2017, 09:14 AM
The circuit diagram of the object counter is quite similar to my previous project (digital stopwatch circuit) but a bit complex. In this circuit we have used a comparator (IC LM358) and an IR transmitter and receiver pair to detect an object. And then we used an IC of 555 timers to generate a pulse to activate the seven-segment decoder (CD4033) and two seven-segment common-cathode display units are connected to a 7-segment IC decoder. 555 IC timer is set to mono-stable mode to generate pulse. An LM7805 voltage regulator is used to provide a constant 5-volt power supply for the circuit. And a 9-volt battery used to power the entire circuit.
Working
In this circuit we detect the object using the sensor and the IR comparator and then apply the comparator output to the mono-stable multi-vibrator. This mono-stable multi-vibrator generates a fixed time pulse that can be adjusted by the given formula.
T = 1.1RC
In this circuit we have selected R1 is 10K and C1
After obtaining a pulse from timer 555, we apply it to the clock pin of the 7-segment decoder (U4) and then perform the signal (pin 5) to the clock pin of another segment decoder (U3). After obtaining the 555 timer pulse 7 counter segment changes the numeric value of the segment display. And when the count of numbers reaches 10 in the U4 decoder, it sends the execution signal or the pulse to seconds of the segment decoder (U3) and then the second screen changes its numerical value. And this process is repeated again. This object counter circuit can count 00-99.