How Does Simple Digital Stopwatch Circuit Diagram Work?

This circuit is the simple form of digital stopwatch. This circuit uses IC1 timer LM555, IC2 4-digit counter MM74C926. In the initial state, the 7-segment will display 0000 (4-digit). If the switch S2 is pressed, timer will start to count. Push S2 again and the timer will stop. The rotary switch is used to choose the time period. Pin 1 will turn the time in 1 second basis. Pin 2 will turn the time in 0.1sec basis. Pin 3 is used to reset.

Simple Digital Stopwatch Schematic Diagram

Here is the circuit :

Digital Stopwatch Circuit Diagram by documentbuzz.com

Simple Digital Stopwatch Circuit Diagram Components

1. Polar Capacitor C1 : 3.3uF/10V
2. Capacitor C2 : 0.01uF
3. Resistor R1, R4, R5, R6 : 10 kOhm
4. Resistor R2 : 3,9k ohm
5. Resistor R3 : 200k ohm
6. Resistor R7 : 4.7k ohm
7. Resistor R8-R14 : 330 ohm
8. Resistor R15-R18 : 1k ohm
9. Potentiometer VR1 : 22k ohm
10. IC1 : LM 555
11. IC2 : MM74C926
12. Transistor T1,T3-T6 : BC547
13. Transistor T2 : BC557
14. Switch S1 : Rotary Switch
15. Switch S2 : ON/OFF
16. Switch S3 : Push Button
17. Dis1-Dis4 : 7segment common anode
18. Power Supply 5V DC

Estimated Price : $5

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