Technically if I want to desgin AVR as a beginner I mean automatic voltage regulator for at lease 15kva generator upward can you link up with circuit diagram.am from Lagos Nigeria.
You will find some schematics to guide you but the essential thing to do is to understand how an AVR is supposed to work, what are the required inputs and outputs and what is a closed loop control ... some work to do before you can attempt to just expect someone to send you a working circuit with the details all ready to go.
The price of this board in the market is $60, if you build it by your self it costs you much much more and never be the same and takes long time (months).
The time of building your own project is over unless you need something is not available in the market.
The initial information needed that will help you decide and must be first established before any circuit diagram becomes relevant to you are:[p}
1) How much or what range of voltage fluctuations are experienced in your area? This will be your (Transformer Input Voltage)
2) What will be an acceptable range of voltage variation for your applications? (Output Voltage +/- %)
3) Type and voltage regulation requirements of your load(s)?
4) What kind of electronic parts needed for this project are readily available in your area?
5) How much money you are willing / capable of spending for this project?