76Views7Replies

# Simplest way to build a stopwatch (max 59 minutes and 59 seconds i.e, 59:59) without coding or programmable ics? Answered

Hi,
I am trying to make a stopwatch that counts from 1 second to 59 minutes. Almost all the circuits that I've seen involves some kind of coding or programmable ics. But I don't want that. I'll be using a quartz crystal as my 1 Hz base and 4 individual 7 segment displays ( 2 for seconds and 2 for minutes). I know how to use decade counters to count till 60 seconds but I need help for turning 60 seconds to 1 minute and reset the 7 segments that represent seconds. In a nutshell, I would like to know how to change 00:59 to 01:00.
A counter that updates after every six "inputs" could solve everything. A link to a a circuit diagram would be helpful too.

Tags:

## Discussions

Look for divide-by-N circuits, probably based on the CD4510

https://www.instructables.com/id/24-Hr-Digital-Clock-only-with-basic-CMOS-Chips/

I had considered that one before but decided against it due to the large number of ics required.

How about this one

http://www.electronicshub.org/wp-content/uploads/2...

I will make 2 such pairs and feed the output from the And gate U5B which resets U2 to another the CD4510's carry in, whose carry out would in turn go to another Cd4510's carry in. Basically just designing another pair like shown in the link to display the minutes.

I sense a school project?

Are you sure your crystal is 1 Hz?

Looping an output of the decade counter back to the reset will reset on a particular count. You may need to and more then one output together to get the reset you want.

For cct diagram - if there is one - you can google just like we can.

Not really a school project. Just a hobby.

Of course not! The crystal is of 32768 Hz and I divide it down all the way to 1 Hz.

I am not sure I completely get you. I want a count and reset when the ten's place of seconds reach '6'.

By any chance are you suggesting that I use a logic circuit that gives a reset to the counter only when it receives the unique code that shows '6'.

By any chance are you suggesting that I use a logic circuit that gives a
reset to the counter only when it receives the unique code that shows
'6'.

Yes, that's the standard method