I need to design a circuit for controlling the speed of a motor of a fan.
Its operation should be like this one switch for turning on/off and another three for speed.
So, it would be really helpful if anybody could give me any idea about how should I proceed.

 

You should proceed by explaining what steps you have taken to try to solve the problem, describing where you are running into difficulty and, if possible, what specifically you are asking for help with.

 

Also, what fan you do you want to control? Some types of fan motors cannot be speed controlled.

Ken