

Electronics Lucky Number
The circuit is simple and self explanatory. IC1, a NE555 timer, is used as astable mode to generate clock pulses at a rate of about 20 Hz. The frequency can be varied with the help of potentiometer VR1.
The clock pulses from the timer are fed to clock input of IC2, a decade counter. The outputs of the counter are decoded by IC3, (BCD to seven segment decoder/driver) which drives a common anode display (DIS1) to show from figure 0 to 9.
On pressing switch SW1, IC1 starts working, with the display changing from 0 to 9. Capacitors C1 is charged during this time.
Once SW1 is released, the capacitor discharges through resistor R3, VR1, R1 and R2. Thus, the frequency of IC1 decrease (and hence the rate of changing figures on the display) and ultimate becomes zero, once C1 has totally discharged thereby stopping the displayed is enhanced by the time for which SW1 is pressed. So, the random effect is natural outcome.
PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon)
R1 = 100 KΩ
R3 = 1 KΩ
R4 – R10 = 330 Ω
VR1 = 100 KΩ
Capacitors
C1 = 47 µF/10V
C2 = 0.47 µF
C3 = 0.01 µF
Semiconductors
IC1 = NE555
IC2 = 7490
IC3 = 74247
D1 = 1N4001
DIS1 = FND507 or LTS542
Miscellaneous
SW1 = push to on switch
nic
where i can find all of those stuff? anwer kindly please
in some circuits some values r missed.. can u pls revise the circuit and give the values for all. it is so useful site for me…
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