This is our DLD project presentation slide .We are the Students of East West University.

1. WELC
OMETO OUR
PRESETATION

2. Digital Stopwatch
Presented By
Safrat Alam 2017-1-55-022
Samyul Kabir Samy 2017-1-55-032
Abu Anwar MD Abdullah 2017-1-55-038
Presented to
Zahidur Rahman
Lecturer
Dept. of ECE

3. Digital Stopwatch
Often we need stopwatch to differentiate the time of two events.

5. Components
IC 4033 - 2
555 timer IC -1
Common Cathode 7 Segment Display -2
150 Ohm -1
100K resistor -1
33K resistor -1
56K resistor -1
10uF capacitor -1
On/off switch -1
Push button -1
Bread board -1
9 Volt Battery -1
Battery Connector -1
LED -1
Voltage Regulator 7805 -1
Connecting wires

6. IC CD4033
This is counter and seven segment decoding in one package IC which is very easy to
interface with seven segment displays. This is fully static counter operational IC and ideal
for low power displays. This IC can be used for decade counting seven segment decimal
displays, frequency division seven segment decimal displays, clocks, watches, timers,
counter/display driver for meter applications.

7. 555 Timer Ic
555 is very commonly used for generating time delays and pulses. It is an
8pin timer IC and has mainly two modes of operation: monostable and
astable. In monostable mode time delay of the pulses can be precisely
controlled by an external resistor and a capacitor whereas in astable mode
the frequency & duty cycle are controlled by two external resistors and a
capacitor.

8. IC 7805 (Voltage Regulator IC)
7805 is a three terminal linear voltage regulator IC with a fixed
output voltage of 5V which is useful in a wide range of
applications.
PIN
NO.
PIN
DESCRIPTION
1
INPUT
Pin 1 is the INPUT Pin. A positive unregulated voltage
given as input to this pin.
2 GROUND Pin 2 is the GROUND Pin. It is common to both Input
and Output.
3 OUTPUT Pin 3 is the OUTPUT Pin. The output regulated 5V is
taken at this pin of the IC.

9. Working of Digital Stopwatch Circuit
 In this stop watch circuit we have generated one second delay by using 555
timer based astable multivibrator. By using some calculation we can easily
generates one second delay. In astable multivibrator there is two resisters and
one capacitor is responsible for delay by charging or discharging capacitor
through resistors.
 When we ON the stopwatch (by start/stop button) it start counting from zero and if
we turned OFF the same button then counting is stop or pause until again turned
ON the same button or press reset button. There are two seven segments, so this
stopwatch circuit can count 00-99 seconds time.

10. Digital Stopwatch Limitations
1. The circuit does not display the actual time, but rather the count of clock pulses.
2. The use of digital counter ICs produces a time delay in the whole operation, because of the propagation delay
3. This is a theoretical circuit and may require changes.