DS18B20 thermo sensor

1-Wire Digital Thermometer
Manufacturer: Maxim Integrated

Used as:

• Thermo sensor in MFM-waterlevel to correct for air temperature dependency of ultrasonic distance sensors.

• Water temperature sensor.

Tests

To get a better indication of the practical usability of this sensor test were carried out.

Preparation

For the tests 6 waterproof sensors were prepared by placing a TO-92 package DS18B20 on the bottom of a stainless steel tube. The sensor is fixed in the tube using 2-component polyurethane resin. To improve mechanical stability of the cable connection a piece of shrink tube was used.

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Accuracy test

The sensor output has been compared to the readings of a calibrated Pt100 sensor (Dostman P705) in water over a temperature range of 0 to 40 ^oC.

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Typical graph for the deviation of the DS18B20 versus temperature.

Mean accuracy for the 6 tested sensors: 0.1°C (mean deviation 0,1 °C).

Response test

To test the response time the sensors are alternately immersed in water of different temperatures.

Graph: From 20 to 0 ^oC and backwards

Graph: From 17,8 to 16 ^oC and backwards

Both graphs:

X-axis: time [seconds]
y-axis: temperature [ ^oC]

Results:

𝛅T 20°C

𝛅T 1,8°C