This project uses IC LM35 as a sensor for detecting accurate centigrade temperature. We can activate or deactivate a device at a particular margin temperature. For simplicity we have used 2 LED for indication of both low (Green) and high (Red)
Here is a Simple Temperature Display Circuit using LCD (Liquid Crystal Display). For Heat Sensor we have used IC LM35 (Precision Centigrade Temperature Sensors) whose Output voltage is linearly proportional to the Celsius (Centigrade) temperature.
Here is an interesting electronics project to detect if there is raining or not. Same circuit can also be used as water level indicator or as a tank overflow indicator.
Electronic eye has much use in this electronic age, also Known as magic eye. It can be used as an automatic guest indicator at the door, if fitted on the bottom of the door entrance. Once it is installed at the door there is no need to install a call bell. It can also be used at homes or in banks as a burglar alarm.
Here is very simple circuit to control a speed of a DC motor according to the room temperature. It uses LM35 as heat sensor. Very few component is used in this project.