BCD Clock

[demo]

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

 

[Bob Monsen]

demo wrote:

hi all,
I`m trying to build a BCD clock using bcd counters but i`m having
problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes) If anybody has an
idea how to fix this please help!

Perhaps you could use a presettable bcd counter for the hours?

--
Regards,
Bob Monsen

If a little knowledge is dangerous, where is the man who has
so much as to be out of danger?
Thomas Henry Huxley, 1877

 

[Bill Bowden]

i`m having problems resetting the clock from 12:59 to 01:00; instead the clock
restarts counting from zero 00:00 (hours and minutes)

The BCD clock at:

http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm

Works like this:

You get a falling edge at pin 1 of the hours counter which advances the
counter to 13 hours. This produces a high level at pins 2 and 14 which
resets the counter to 0.

So you have that much working.

The reset signal stays high for a few milliseconds determined by the RC
at pin 11 of the inverter.

Pin 12 of the next inverter will move high a short time after pin 10
moves low, which applies a high level to pin 1 (clock input) of the
counter. When pin 10 moves back high, pin 12 will move low a short time
later applying a falling edge to the counter which advances it from
zero to 1. So, it's now 1:00 PM instead of 0.

It should work if you use the right parts.

-Bill