Making a temperature probe

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Creative25
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Making a temperature probe

Postby Creative25 » Sat Sep 15, 2012 9:40 pm

Hi
I am using a MCP 9800 temperature sensor for measuring temperature.
I have soldered it on a 4 core a cable, and everything is working fine.
Somehow I need to make it water proof since I would like to use it in a fridge.
I thought of covering it with epoxy glue. Is this a good way or are there better solutions?
Best Regards:
Uli

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Re: Making a temperature probe

Postby Enamul » Sat Sep 15, 2012 10:20 pm

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Re: Making a temperature probe

Postby petesmart » Sun Sep 16, 2012 7:37 am

Hi Uli,

A couple of points to keepin mind:

What ever you use to waterproof should be kept thin as possible to allow heat transfer,

Also the material you use should should have good heat transfer characteristics.. If it acts as an insulator then your temp readings will be inaccurate.

Be careful with epoxy, I have had situations as the expoy dries it places stress on component leads, on a couple of occasions destroying the component. Silicon grease helps here..

Good luck

Pete
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sorry about that Chief!

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Re: Making a temperature probe

Postby Creative25 » Sun Sep 16, 2012 10:35 am

Hi Pete,
What kind of components were destroyed by the epoxy, small or large components?
How thick was the epoxy layer can it even happen with a thin layer?
How do you apply silicone grease? Do you mean silicone grease instead of potting or silicone grease on the component?
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Uli

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Re: Making a temperature probe

Postby petesmart » Sun Sep 16, 2012 7:36 pm

Hi Uli,

It was components with axial leads capacitors, discrete devices etc. As the epoxy dried it expands basically ripping the legs/leads from the components. Yes it was a large potting block of epoxy.

the way we solved this was to place a thin layer of silicon grease around the component, then apply the epoxy..

I would keep the epoxy as thin as you can to ensure maximum heat transfer from external to surface of the chip.

Just a thought, perhaps if you glue a small piece of aluminium to the top of the chip at right angles, which protruded thru the epoxy, sought of like a heat sink in reverse? It would contact the heat into the potted block which means that your epoxy thickness would not have to be as critically thin? Possibility be worth an experiment.

welcome comment from others on this one.

all the best

pete
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Re: Making a temperature probe

Postby Steve001 » Fri Sep 28, 2012 12:33 pm

just seen this post , I know that you would like to use the one you have but maybe this would be of help

http://proto-pic.co.uk/temperature-sens ... f-ds18b20/

Steve
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Re: Making a temperature probe

Postby Enamul » Fri Sep 28, 2012 12:50 pm

Hi Steve,
That's really good for lots of application..Thanks for the link.
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