can any one till me

Audioguru

Joined Dec 20, 2007
11,248
The capacitor values for the 555 oscillator are much too low and it will not work.
The datasheet shows 1000pF as a minimum value.

I think the values of R3 and R4 are much too low and cause the 4511 ICs and LED displays to burn.
 

beenthere

Joined Apr 20, 2004
15,819
The logic is wrong, too. While labeled as 74LS93, the counters have the pinouts of 74LS90's.

A digital clock has to be able to count higher than that circuit. Minutes and seconds need counts of 0 - 59, hours 1 - 12.
 

Papabravo

Joined Feb 24, 2006
21,094
thanks
but the cct works properly
i need to know the basic work>>>
how does it work
purpose of the ic's
If the circuit wa designed and implemented correctly, which it is not.
The 555 should be configured as an astable multivibrator whose purpose is to generate a square wave at some convenient frequency. The counters will count rising edges of the 555 output and the 4511 is a BCD to 7-segment decoder.

This circuit would only work in some parallel universe, or there are details of which you and we are not aware.
 

bertus

Joined Apr 5, 2008
22,266
Hello,

The 555 has to low value capacitors.
The two counters will count until 9.
So the circuit will count 0 - 99.
The resistor for the led is to low and you shpuld use resistors for each segment (not the complete display).

Greetings,
Bertus

PS in simulation it may look to work, but practice is different.
 

radiohead

Joined May 28, 2009
514
the 555 is a poor choice for an accurate clock circuit anyways. For accurate timing, you would need a crystal controlled oscillator.
 
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