precise driving circuit

Hi everybody,
I want to build a precise driver circuit.
Whenever i'm measuring 5v it should give some indication(led flash,beep sound.etc..)
if the input voltage is in between 4.8 and 5.2v, then only my circuit will drive led or beeper.
if the input voltage is not in the above range,then the driver circuit should not work.
I'm having a simple transister switching circuit but the tolerance is very high.if the voltage is exactly 5v(4.8-5.2)then only i need some external indication.my driver circuit is giving output even for 3.3v.
Waiting for a reply,
Thank u.

why not use two comparators and an AND or NAND gate? setting precise voltage thresholds is very easy with a comparator circuit... just set one so its output is high whenever the voltage is above 4.8v, and the other so its output is high whenever the output is below 5.2v, that way when they are AND'ed together the output will only be high when the input is in the range 4.8-5.2v.

I don't really understand what you are trying to do, but do you have a stable +5 volt source available?