I'm going to build a AC fan controlling system according to the temperature. In simple words, the fan should be able to automatically control its speed according to the temperature of the environment. I hoped to use PIC16F877 and LM35 temperature sensor. I found these problems..

1. How to convert 5V/DC current from PIC to 230V/AC current in fan
2. Should i use PID controller? how?
3. Do PIC 16F877 has enough memory to do this?

Can u please give ur suggestions....

 

help me please

 

That is a bit elaborate - why not use a thermostat to do the controlling?

If you need to use the PIC, use a solid state relay to directly control the fan. It is not practical to try to step up 5 volts to 120 AC.

 

This might help.

http://electronicdesign.com/Articles/ArticleID/20639/20639.html