Three temperature switch circuits

Electronic temperature control circuit for imported car air conditioners. It utilizes operational amplifiers A1 and A2, specifically the LM393 model. An adjustment potentiometer (RP) is included, allowing modification of the temperature range. The adjustment range includes a power temperature setting of 6 to 18 degrees Celsius, with a shutdown temperature of 15 degrees Celsius. The temperature difference for the opening and stopping operation is 3 degrees. A negative temperature coefficient thermistor (R) is employed, with the RR03-2 type being suitable, which has a resistance of 3k at 25 degrees Celsius, or alternatively, a MF51 type can be used.

The electronic temperature control circuit is designed to regulate the temperature within imported car air conditioning systems effectively. The circuit employs two operational amplifiers, A1 and A2, which are configured to form a comparator setup using the LM393 integrated circuit. This IC is known for its low power consumption and high-speed performance, making it suitable for automotive applications where reliability is crucial.

The adjustment potentiometer (RP) facilitates user-defined settings for the desired temperature range. The operational amplifiers compare the voltage from the thermistor against a reference voltage set by the potentiometer. The thermistor has a negative temperature coefficient, meaning its resistance decreases as temperature increases. This characteristic allows the circuit to accurately monitor the ambient temperature and adjust the air conditioning system accordingly.

The specified temperature range allows for operational flexibility, with a power temperature setting adjustable between 6 and 18 degrees Celsius. The shutdown temperature is set at 15 degrees Celsius, providing a safety threshold to prevent the system from operating outside optimal conditions. The temperature differential of 3 degrees ensures that the system does not engage and disengage too frequently, enhancing the longevity of the components involved.

The use of the RR03-2 thermistor, with a resistance of 3k ohms at 25 degrees Celsius, is ideal for this application, providing the necessary sensitivity for accurate temperature readings. Alternatively, the MF51 thermistor can also be utilized, offering similar performance characteristics. The design of this circuit ensures that it can be integrated seamlessly into existing car air conditioning systems, enhancing user comfort through effective temperature regulation.Electronic temperature control circuit on an imported car air conditioners. Operational amplifier Ai, A2 using LM393. Adjustment potentiometer RP. Temperature range can be chan ged. Adjustment range: Power temperature 6 ~ 18, 3 ~ shutdown temperature 15 C, the temperature difference between the opening stop of 3. Negative temperature coefficient thermistor R. RR03-2 type can be used, 25 resistance is 3k, Q, or MF51 type.