A Temperature-Controlled Fan Speed Controller is an analog electronics circuit that aims to control the speed of a DC fan based on the ambient temperature. The system uses an LM35 temperature sensor to measure the temperature and an operational amplifier as a voltage comparator to compare the sensed temperature with a user-set temperature set-point.

When the ambient temperature rises above the set point, the fan speed increases to provide additional cooling. Conversely, when the temperature is below the set point, the fan speed decreases or remains OFF to conserve energy.

This project is suitable for applications where maintaining a specific temperature is essential, such as electronic equipment cooling, home automation, and climate control systems.

LM35 Temperature Sensor

• Operational Amplifier (e.g., LM358)
• NPN Transistor (e.g., 2N3904)
• DC Fan (12V)
• Potentiometer (10k ohms, for adjusting sensitivity)
• Resistors (for voltage divider and biasing)
• Capacitors (for noise filtering, optional but recommended)
• Breadboard and jumper wires
• Power supply (e.g., 12V DC adapter)

Draw the electrical circuit diagrams with the values of resistors and capacitors as I need to make the prototype design and test it.