great, thanks for that ag
. i can get those componets through the uk version of the site you mention (farnellinone)
last set of questions (hopefully!):
1) the LED, is 2.5V a minimum rating, as they are a lot cheaper when they are 5V?
2) the opamp chip has 4 opamps on it?
3) adding in the other inputs. taking from where you suggest, i only need the one voltage reference IC? is it possible to tap at the -ve input to the opamp for the other channels instead, as i don't need to be able to adjust the threshold or opamp gain independently.
4) there are loads of different kinds of resistors, is there anything i should be aiming for, or will the cheapest do?
5) is the capacitor you added smoothing out the fluctuations in voltage?
6) is there an equivalent voltage reference IC available here
www.maplin.co.uk (i can't find the one you mention) as there is one locally, so i can buy resistors etc. singly instead of in packs of 25!
thanks for the help, as you can tell, this is my first project, so it's a bit of a steep learning curve.