time delay/ hold circuit

[bonanz]

I know this is something simple but i've done a little searching and can't find what i'm looking for and i can't work it up form scratch for the life of me....

I'm looking for digital logic circuit/gate that everything starts at 0 (low) and then if high is input, the output is high, but only for about 5 seconds, then the output goes low again, nomatter if the input stays high or goes low again.

I hope i explained it clearly, but basically the idea would be, press a button to turn on a LED or something for 5 seconds or so, if you hold the button down it goes for 5 seconds and turns off, if you press it and let go it will hold it for 5 seconds and turn off, either way once the led goes low it is ready to be turned on again.

Thanks in advance guys

[MANOTRONIC]

Hi,
what you need is a 555 timer ic, in "non retriggerable" mode.
If you "google"( 8)) with the words "555 timer" you'll find about
54.000 results :D.The http://www.williamson-labs.com/480_555.htm
for example,looks good.
Hope i have helped a bit. ::)

[mixos]

As manotronic noticed you can use a 555 timer in Monostable mode:
The basic circuit is this:



For circuit description and how to attach a relay visit: http://www.technologystudent.com/elec1/5554.htm

[hotwaterwizard]

This is so cool how did you get the diagram to show it in operation with the timing in progress and working?