Logical Circuit for 24 Hour Digital Alarm Clock

Thread Starter

csastra

Joined Aug 15, 2018
4
Hi, I am writing a report on making a logical circuit for a 24 hour digital alarm clock which rings every 45 mins. How it is set up is that I have the power supply hooked up to the pulse generator which is connected to the second section. The second section is connected to the minute section and the minute section is connected to the hour section. My second section and minute section has the DB10 and DB6 decoder which I understand makes a counter which counts from 0 to 59 seconds. However, I am a bit confused on how to make my hours section. Should I have a DB3, DB5 and a DB10 to make 0-23 or do I just have a DB3 and DB5. This is because from what I understand, if I only have the DB3 and DB5, a the minute section will be connected to the DB5 which will count up to 4 before recycling while initiating the DB3 to count to 2. If this happened wouldn't it make the hour section only count up to 8 hours in total?
The former option makes more sense to me but I am still confused on how to set it up...
Thank you
 

MrChips

Joined Oct 2, 2009
20,216
We don't know what is DBx.

Circuit schematics is the language of electronic circuit design. Show us a circuit and we will be in a better position to help you.
 

Thread Starter

csastra

Joined Aug 15, 2018
4
We don't know what is DBx.

Circuit schematics is the language of electronic circuit design. Show us a circuit and we will be in a better position to help you.
Sorry, I didn't know.
What I meant by DB is the 7490 chip, the decade counter? i think. Which was configured to count to a certain value. eg. DB5 counts to 4, DB 6 counts to 5. I do not have a drawing of the circuit but there is a report that I am looking at as a reference and I attached what they had their circuit set up like.
 

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MrChips

Joined Oct 2, 2009
20,216
You can use a 7490 decade counter for units and a 7492 divide-by-six counter for tens of seconds and minutes.

For 24-hour counter, use the same set up but decode when 24 occurs to reset. You only need to AND two bits.
 

AnalogKid

Joined Aug 1, 2013
8,305
Is a time display required? If not, this can be done with a lot fewer parts.

How long does the alarm sound?

Where are you located?

Is this school work?

ak
 

Thread Starter

csastra

Joined Aug 15, 2018
4
Is a time display required? If not, this can be done with a lot fewer parts.

How long does the alarm sound?

Where are you located?

Is this school work?

ak
yes, im in high school, but i dont take physics.

and im from indonesia

i havent worked on how long it will ring yet.
 

Thread Starter

csastra

Joined Aug 15, 2018
4
You can use a 7490 decade counter for units and a 7492 divide-by-six counter for tens of seconds and minutes.

For 24-hour counter, use the same set up but decode when 24 occurs to reset. You only need to AND two bits.
If i use the same setup as the reference, mt problem is/was i dont really understand how the counter gets from 0 to 24.
 
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