DS18B20 Question

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1

Guys, I have a DS18B20 that I have been using on a breadboard that now needs to go into a proper package for deployment.

At the moment I have been using the full cable length. Is it possible to cut the cable to perhaps 100mm long? It ships with about 500mm of wire and its too long to fit in the deployment box.

Just want to make sure that if I cut the wire it wont screw up the resistance / readings etc.

Thoughts?

Thx
Jon

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Hi Jon,

Looking at the product page for Temperature Sensor - Waterproof (DS18B20) SKU: SEN-11050
The example application does advise using a pull-up resistor but this shouldn’t mean you couldn’t also shorten the device’s lead as that resistance will be negligible relative to the pull-up resistor.

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3

Pretty sure that should be fine. From memory, the ds18b20s send a digital signal so write length should make no difference (just double check the datasheet).

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4

Hey Oliver and all,

While it’s a finicky digital protocol, it’s still a digital protocol, so you should either get accurate measurements or failed measurements (85*C sometimes get spat out on a failed measurement).

The guide from Maxim goes over the main problems when using a bunch of these sensors at range:
https://www.maximintegrated.com/en/design/technical-documents/tutorials/1/148.html

It may not apply to you but it’s a great guide that helped me when I was working with these
-James

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Thanks guys.
I thought some time ago that I had read (probably on this forum somewhere) that it could be shortened but I couldnt find any reference when I searched again.]

I’m already using a 4k7 resistor so all good on that front. I’ll chop it and see how I go!

Thanks again,
Jon

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