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Be at your post.... Help Please

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Caligula

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I need to make sure that certain employees are at their post during the night shift. I have devised a gadget to make sure of this but because I am electronically challenged, I need some help in designing it.

It works like this;

1>.. Key switch activates gadget
2>.. once activated, a count down timer is set at 15 minutes.
3>.. When the timer reaches zero, a LED (A) flashes and activates a second count down timer set at 5 minutes.
4>.. If a reset button (a) is pressed within the 5 minute countdown, return to 2>.. above. If not, proceed to 5>..
5>.. Relay is activated which energises an alarm siren and a second LED (B) lights up.
6>.. Siren will continue to sound until reset button (a) is pressed, once pressed, return to 2>.. above
7>.. LED (B) can only be reset by de-activating the gadget with the key switch.

Please if anybody can help with the design, i would be much obliged :(
 
It would be fairly easy to implement with a few i.cs but easier, perhaps, with a PIC.
 
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