CLD Digital Clock Homework: 555 Timer & BCD Decoder

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Discussion Overview

The discussion revolves around creating a digital clock using a 555 timer and a BCD decoder to drive a 7-segment display. Participants explore circuit design, component selection, and the functionality of the clock, including how to increment the display for hours, minutes, and seconds.

Discussion Character

  • Homework-related, Technical explanation, Exploratory

Main Points Raised

  • One participant seeks assistance in designing a digital clock circuit using a 555 timer and BCD decoder.
  • Another participant clarifies whether the clock is intended to display a 24-hour format or simply count from 0-9.
  • A suggestion is made to include a BCD counter between the 555 timer and the decoder to facilitate the clock's operation.
  • Participants discuss the need to increment the counter based on the square wave output from the 555 timer, with details on adjusting the frequency for realistic clock behavior.
  • One participant warns that a 555 timer may not provide an accurate clock and suggests using a CD4060 or 74HC4060 IC with a 32.768kHz crystal for better accuracy.
  • A participant expresses gratitude after finding a solution, although the specifics of the solution are not detailed in the discussion.

Areas of Agreement / Disagreement

There is no clear consensus on the best approach to achieve an accurate digital clock, with differing opinions on the use of the 555 timer versus alternative ICs. Multiple competing views remain regarding circuit design and component selection.

Contextual Notes

Participants mention the importance of adjusting the frequency of the 555 timer and the need for counters to reset at specific values (e.g., 59 for seconds and minutes, 12 for hours), but do not resolve the implications of these adjustments on overall clock accuracy.

bravo92
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Homework Statement



I want to make a digital clock on hardware using 555 timer and BCD decoder to 7 segment display. Can anyone help me about the circuit ?


Homework Equations





The Attempt at a Solution



I am using the concept to increment the input of BCD decoder with the help of 555 timer but don't know how to do so
 
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Do you mean a 24 hour clock that tells human time or a 7-segment display that goes 0-9 and repeats?
 
You would need a BCD counter between the 555 and the decoder.

The 555 would connect to the clock of the BCD counter and the output would be converted by the decoder into drive for the 7 segment display.
 
@antiphon : I want to make a 7 segment display that goes 0-9 and repeats ... and for hours , minutes as well as seconds ...
@vk6kro : how to increment the counter that runs the clock ?
 
The counter will increment on each rising edge of the square wave from the 555.

So, you can arrange the incrementing rate by adjusting the oscillation frequency of the 555. (you do this by selecting the components that determine the frequency. Making both resistors 470 K and the capacitor 1 uF will get a frequency of about 1.02 Hz)

If you are trying to make this look like a real clock, don't forget that the seconds and minutes counters will go to 59 and then to zero, and the hours counter will go to 12 and then to one.
 
bravo92 said:

Homework Statement



I want to make a digital clock on hardware using 555 timer and BCD decoder to 7 segment display. Can anyone help me about the circuit ?

Homework Equations


The Attempt at a Solution



I am using the concept to increment the input of BCD decoder with the help of 555 timer but don't know how to do so

You are not going to get a very accurate clock circuit using a 555 timer chip. A better solution would be to use a CD4060 or 74HC4060 IC and a 32.768kHz watch crystal. Here is a simple Google search that includes circuit info and a YouTube video:

http://www.google.com/webhp?sourcei...sb&fp=89a2241ee9b71d7a&ion=1&biw=1149&bih=882

.
 
Last edited:
Thanks a lot ... I got the solution ...
 

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