Temperature sensor and DVM interface

The digital voltmeter (DVM) provides a direct reading of the sensor's temperature in degrees Celsius. The temperature sensor IC1 generates a nominal 1 µV per degree Kelvin, which is converted to 10 mV per degree Kelvin by resistors R1 and variable resistor VR1. IC2 is a micropower operational amplifier (op-amp) characterized by low input drift, featuring an internal voltage reference and amplification capability. The primary op-amp in IC1 operates as a voltage follower to buffer the sensor voltage at R1. The secondary amplifier in IC1 amplifies the 0.2 V internal reference to 2.73 V to account for the offset of 273 degrees below 0°C. The output voltage of the system is the differential output from the two op-amps, resulting in a sensitivity of 0.01 V per °C.

The described circuit utilizes a temperature sensor IC (IC1) that converts temperature to a voltage signal. The sensor operates by producing a small voltage output proportional to the temperature in Kelvin, which is then scaled to a more usable range in degrees Celsius. The conversion is facilitated by a resistor (R1) and a variable resistor (VR1) that adjust the output to 10 mV per degree Kelvin, making it suitable for further processing.

The operational amplifier IC2 is specifically chosen for its low power consumption and minimal input drift, ensuring accurate readings over time. The use of a voltage follower configuration in the primary op-amp allows for high input impedance, which prevents loading the sensor and preserves the integrity of the signal. The secondary amplifier's role is crucial for adjusting the output reference voltage, allowing the system to correctly interpret temperatures below freezing by offsetting the readings to account for the absolute zero reference point.

Overall, the output from the two op-amps is a differential voltage that directly correlates to temperature changes, with a sensitivity of 0.01 V per °C. This level of sensitivity is beneficial for applications requiring precise temperature monitoring, such as in HVAC systems, laboratory experiments, or environmental monitoring. The circuit design emphasizes stability and accuracy, making it a reliable choice for temperature measurement applications.The DVM gives a direct indication of the temperature of the sensor in degrees Centigrade. The temperature sensor IC1 gives a nominal 1 µ per degree Kelvin which is converted to 10 mV per degree Kelvin by Rl and VR1. IC2 is a micropower, low input drift op amp with internal voltage reference and amplifier. The main op amp in IC1 is connected as a voltage follower to buffer the sensor voltage at Rl. The second amplifier in IC1 is used to amplify the .2 V internal reference up to 2.73 V in order to offset the 273 degrees below 0°C.

The output voltage of the unit is the differential output of the two op amps and is thus equal to 0.01 V per °C.