SCR as a switch control for automatic light dimmer

[lizxay]

Hi guys, can u guys help me on this?? I want to design and construct an automatic light dimmer circuit that controls the energy delivered to a 12V or 24V DC light bulb corresponding to the ambient light intensity.
The control of energy will be established through switching action to improve efficiency and i will use SCR as means for switching.
I have no idea where should i start. any ideas guys? thank u very much and hope to hear from u guys soon =)

 

[MATLABdude]

Please do not cross-post to multiple subforums; if it's homework, post here, but if it's general consultation sort of stuff, post in the EE forum. There are already several replies in the other thread.