Remote thermometer

Posted on May 16, 2012

The low output impedance of a closed loop op amp gives ideal line-noise immunity, while the op amp's offset voltage drift provides a temperature sensor. Using the op amp in this way requires no external components and has the additional advantages of a hermetic package and unit-to-unit mechanical uniformity if replacement is ever required. The op amp's offset drift is amplified to drive the meter by the LTC1052. The diode bridge connection allows either positive or negative op amp temperature sensor offsets to interface directly with the circuit. In this case, the circuit is arranged for a + 10°C to +40°C output, although other ranges are easily accommodated.

Remote thermometer
Click here to download the full size of the above Circuit.

To calibrate this circuit, subject the op amp sensor to a +10°C environment and adjust the 10 °C trim for an appropriate meter indication. Next, place the op amp sensor in a +40°C environment and trim the 40° C adjustment for the proper reading. Repeat this procedure until both points are fixed. Once calibrated, this circuit will typically provide accuracy within ± 20 C, even in high noise environments.

Leave Comment

characters left:

New Circuits



Popular Circuits

Function Oscillator using 8083
Simple Curve Tracer Circuit
accelerometer amplifier circuit
switching between parts circuit pulse input
Electronic Thermostat and Relay Circuit
IC Shift Register Chip
Ammo Box Sequencer
Raspberry Pi Driving a Relay using GPIO
Ballroom synchronous voice switching circuit with music
XTR108 reverse voltage and overvoltage protection circuit diagrams
Asia ultrasonic remote control circuit
With NE555 make double touch light switch 2