dc motor control by diac And triacs

Try saying "please", then.

The problem with these, is that they are trying to get assistance to design a project, that if they went to collage and learn't the practical side of devices, they wouldn't have a problem designing.

The circuit is quite simple, but the idea is to goto manufacturers web sites and read up on "How do triac's work" get a complete understanding on how they work, and whats needed for controlling them, if not, your going to be trying to build something you don't fully understand, then you'll be back later to try and get help cause it didn't work ;o(