I want to control the speed of a fan automatically as per the temperature of the room i.e if the tremperature rises the fan should run slowly and vice versa

Please provide the circuit to control the speed of a fan automatically as per the temperature of the room i.e if the tremperature rises the fan should run slowly and vice versa

Some fans come with this feature. You may also be able to purchase an aftermarket remote/receiver kit that has this feature.

Amazon.com: Westinghouse 7787400 Thermostat Ceiling Fan and Light Remote Control for Fans: Home Improvement (http://www.amazon.com/Westinghouse-7787400-Thermostat-Ceiling-Control/dp/B000N1DM9M)