help!!!

could anyone help me create a timing circuit which:
.... has a capability of timing from 30 minutes to 2hours
.... using two 555 ic to create one ic for the main timing and the other for changing the time a LED stays working for and pulse speed of it

thanx [/img]

It is hard to get any kind of accuracy for long periods
using only timer chip. I would recommend using counter(s) to
achive long times. Check the datasheet for 4020

**broken link removed**

It's 14-bit counter (divide by 16384).
Half an hour is 30*60=1800 seconds (16384/1800=9.1Hz).
Two hours is 2*60*60=7200 seconds (16384/7200=2.2Hz).

So all it takes is to make adjustable oscillator that would cover
range 2-10Hz (maybe flash LED as well so you can easy tell the
difference).

timer



you can also try CD4536 and you can also use the site cited by panic mode