Electronics type sensors circuit...will it work

Hey,im doing a project where i have to make a simple alarm that detects if the light level reaches past a certain amount.I have come up with an idea with the help of a few websites but im stil not shure if one will work.
thx

the one part thats pins are G,A,C is a scr
it uses the rf tranmitterand reciever from http://www.robotshop.ca/home/produc...elemetry/on-shine-high-sensitivity-tx-rx.html

Look at the application notes in data sheets for comparators

colin,

Looked at your drawing and link.

On the link, the information regarding the inputs/outputs is missing.?

Your transmitter SCR will never switch ON, the Gate is grounded [0V].

The Receiver output, may not be able to drive an SCR, if it did, how would you switch OFF the SCR.?

As already suggested, have a look at some comparator information.