| Electronics > Projects, Designs, and Technical Stuff |
| Digital Clock |
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| Sangharsh Sharma:
I've been trying to build a 12 hour format digital clock. As far as I think, I've done everything correctly. But the problem is as soon as I connect the power supply, the count just starts from random as if the circuit isn't working. What do I do so that the count starts from 00:00:00 in a correct manner? I've attached an image below. The simulation works correctly but it isn't the same here. |
| NorthGuy:
You need a reset signal which puts all the flip-flops into a known state. To keep the reset asserted at the beginning you can use a simple capacitor curcuit. When you power up, the capacitor charges slowly and the reset gets de-asserted only when the capacitor is charged. |
| edavid:
There is no need to have a reset circuit, since you need to set the clock anyway (unless you plan to set it by turning it on at midnight). |
| Dundarave:
Just wire in two small push-buttons to manually advance the “hours” counter and “minutes” counter. (Seconds too, if you want to be anal about it, lol) Each time you power up, just click the buttons to advance the values to match the correct time. |
| jbeng:
Do you have a schematic you can post? If not, what is the part number of the counter chips you are using? |
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