rq3
Senior Member
Basically just a heads up. Appliances always seem to fail when one is on vacation. Sure enough, on my return from the Caribbean yesterday, the fridge was a bit warmer than usual. One of the three picaxe controlled DS18B20 temperature sensors on my controller board had failed! No apparent reason. A new one fixed it right away, and the board has otherwise been performing flawlessly for many months. The failed unit displayed a constant zero degrees celsius.
I suspect moisture induced failure of the sensor, and have potted the new sensor in a small brass tube with technical urethane. The sensor gets thermally cycled from -17C to +7C, and sees quite a bit of condensation. Epoxy is too rigid, and may stress the leads, while the urethane is designed for potting thermally cycled devices from -72C to +120C, and has very low moisture transmission. Hope this helps someone!
I suspect moisture induced failure of the sensor, and have potted the new sensor in a small brass tube with technical urethane. The sensor gets thermally cycled from -17C to +7C, and sees quite a bit of condensation. Epoxy is too rigid, and may stress the leads, while the urethane is designed for potting thermally cycled devices from -72C to +120C, and has very low moisture transmission. Hope this helps someone!
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