Almost there and giving up.....

Yeah, although its Saturday and what perceived to be a quiet day, it was not. I ma stuck in this project and there was no one I could talk to for ideas. It also did not help that THAT SOMEONE for some unknown reasons, caused my Notebook to go crashing. And it also did not help that the same SOMEONE called when I was soldering, causing a short in the board and killing one IC when I shouted and cursed at him.

This was not an easy project as I thought it would. I mean, how difficult was it to countdown from '999' to '000' and stop there until it is being reset? The answer, my friends, is easy and not so easy, depending on how and which solution you're aiming at.

The easy way
This was the route I took since the initial description was to have it countdown from 999 to zero. All I have to do is to get some off the shelf electronic kits and its done. And it fits my timetable perfectly. No problems, right?

Wrong.

You see, the problem starts when it was needed to count down from '999' as the circuit starts with '000'. Once I got a copy of the IC's datasheet, I realised why. And so, to get it start from '999' I would now have to hotwire the original circuit to load in the value '999' instead.

And then, as luck would have it, there is no clock signal to the kit which I must buy separately. And it must make the circuit count down very fast. So, I have to modify the kit to do that.

The third problem is that it must stop counting at '000' until a 'Reset' button is pushed where it would go to '999'. Which again, the datasheet proves the IC does not do that. So, this means I would have to obtain more ICs as I would need a few logic gates to do this.

Let's see, our original 7 IC circuit is now being
expanded to a few more ICs. And when it does
work, boy, its going to kill the batteries.

This is the circuit I am testing out on the white
prototype breadboard. It involves three ICs, a
transistor and a switch-over relay. My only fear
is that the circuit would be too fast to for this
sub-circuit to 'catch' the signals.

The not so easy way.
This is the alternative soluton to the same design but the end result is the same and/or even better. The catch? You have to learn the microprocessor's programming language. Compared to the 'old school' solution above which not only uses more than ten ICs, this one uses only one. Because of that, it saves power too. This is actually my backup plan and after weeks of trying to figure things out, it just came to me this afternoon. So, I'll just have to get the IC next week and do the testing, see if this idea works.

This one little IC can take on all 10 uncles and
without breaking a sweat. The only one sweating
is me, trying to figure how to tell it to work.......