does anybody knows the debouncer circuit and alarm circuit? i really need at least 10 debouncer and 10 alarm circuits. Thank you.

 

Have you done any research on this homework problem at all yet? A search on Ganssle and this forum will help. Note, for the logic-based designs, you can switch logic chips. I made one with an XOR chip, for example.

There was a 555 debounce circuit shown here: http://www.mitedu.freeserve.co.uk/Circuits/Switching/debounce.htm

THE ABOVE LINK IS DEAD, but the circuit is also shown here: http://forum.allaboutcircuits.com/showthread.php?t=38780

John