Advantages and disadvantage of digital object counter

Abstract

We need following components for making an object counter

1. 555- configured in monostable mode(automatic dark sensor using 555)

2. 555- configured in Astable mode

3. 7490- decade counter- Click here to get the datasheet

4. 7447- BCD to seven segment display- Click here to get the datasheet.

5. Seven segment display- Common Anode



Here, CC-Common Cathode and CA-Common Anode.



6. Resistors- see the schematic

7. Capacitors- see the schematic

8. Light dependent resistor (LDR)

9. LED

10. Power supply

There are basically three modules in object counter:

555 timer configured in monostable mode.
555 timer configured in astable mode.
Counter module.
555 timer configured in monostable mode is a simple automatic dark sensor circuit that gives output when light falling on LDR is blocked. Pin 3 of monostable circuit has been connected to pin 4 of astable timer. When monostable circuit generates output, astable mode timer starts giving pulses to the counter module.

Frequency for counter module is set up using R4, R3 and C2.

7490 acts as a decade counter and 7447 uses the output of 7490 to display numbers on seven segment display.