Temperature Threshold Range Adjustable 10 to 100 Degree Centigrade using Multiturn Trimmer Potentiometer. The complete system is shown in Figure 3 with the temperature sensor and fan control logic.Fan Load Up to 1Amp Continues (Maximum Load 4Amps).The fan runs until the temperature drops less than the set point. When the sensor output is above the set point, LM358 provides a high output which triggers the MOSFET, and finally, the fan goes ON. The sensor senses the temperature, the output of the sensor rises as the temperature rise, and the comparator compares the sensor output with the threshold voltage of the PR1 trimmer potentiometer. Plug and play controller with a 4 m cable with a 3.5 mm 4 pole jack. LM35 can be mounted directly on the heatsink using silicon glue or with help of a mechanical fixture for proper temperature sense. Temperature and Speed fan controller for noiseless and easy to use control of EC fans. Q1 MOSFET DMG3418L-7 can handle current up to 4A. Capacitor C1 helps in noise control while Fan is ON/OFF. Capacitors C2 and C3 are bypass capacitors, D2 is a clamp diode to protect the Q1 MOSFET from reverse electromagnetic noise coming from the fan. LM35 is used as a temperature sensor, it outputs an analog output voltage that is proportional to temperature. LM358 is used as a comparator, and a trimmer PR1 is provided to set the temperature threshold (Fan ON trigger point).

The project is built using a very cheap LM358 OPAMP. The project presented here is a low-cost solution for heat management of the heatsink and various equipment that requires automatic control of a cooling Fan.

Temperature fan controller