I've made a simple stopwatch using 3 seven segment LED display of which
first you for displaying 10th part of seconds another for second and third one for multiple of 10 inn seconds.
I used 555 timers in astable mode which gives signal per 1 second to IC 4033.
IC 4033 is johnson decoder ic and BCD IC. As signal comes from 555 timer IC 4033 converts into binary code and sends to 7 segment display.
Timer speed can be adjusted by rotating preset clockwise or anticlockwise.
Circuit works between 8-12V .
As I dont have images of circuit while i was making but I made video, please watch this .
Step 1: Gather the Components Required
ALL RESISTORS ARE OF 1/2W
R1-R21 -150 ohm
R23- 10k ohm
R25- 100k ohm preset
R26 & R27 -10k ohm
CAPACITOR C1- 1uf,25v (electrolytic)
LED green colour
2× NE555 with 8 pin IC base
3×CD4033 IC with 16 pin IC base
3× Common cathode 7 segment display
3× push buttons
Step 2: Place the Components
Above I given circuit diagram.
Place every components according to that and place IC base instead of IC as while soldering the high temperature may damage your IC internal circuit.
and there are two connections for 6th pin of IC 4033,that's not right.
pin 6 of IC should goes to seven segment and the other 6th pin shown in circuit diagram is actually pin no 8,so be careful while soldering.
Step 3: Adjustment of Stopwatch
adjusting the preset ,increases or decreases speed of timer so while setting stopwatch, match the time with your mobile phone timer.
Stopwatch can also indicate in 50th part of second by adjusting preset.
If you want brief explanation watch my video I given below
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