thanks for help and now I can control my motor speed by PWM

 

A very general question,Regulated voltage means you never exceed that "pegged" voltage. I think you are looking for remote control of relays. You may wish to spend some time at play-hookey.com. A good start if your just getting into it.

 

Consider using a ULN2003 or ULN2803 if you have several loads to drive. These are peripheral driver IC's that contain seven or eight Darlington pairs respectively, and can sink up to 500mA current per channel.

If you'd like to build an H-bridge for reversible motors, here's a page that you'll find helpful:
http://www.solarbotics.net/library/circuits/driver_4varHbridge.html
There are several other ideas available via the links on the left.