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?
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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
The BCD clock at:
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
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