thermistor protection

Thread Starter

roadey_carl

Joined Jun 5, 2009
134
Hey folks,

I've made a adjustable duel thermometer using a lm393n. I got a pack of thermistors but they don't come protected against liquids... is there any kind of resin I can dip them in without it changing the sensitivity of the thermistor to much?

Thanking yourselfs!
 

SgtWookie

Joined Jul 17, 2007
22,221
You know that an LM393 is a dual comparator, right?

You could use conformal coat to protect them, or clear lacquer. It will reduce their sensitivity a little, but not too much. They simply won't respond quite as quickly.
 

Bychon

Joined Mar 12, 2010
469
I dipped one in clear epoxy and then put shrink tubing on it (and the cable it was attached to) before the epoxy hardened. That slowed the response time down from a few seconds to most of a minute, but it was for a water bed heater where time is considered in terms of hours.
 

Thread Starter

roadey_carl

Joined Jun 5, 2009
134
I think maybe the lacquer might do the trick then... if I use one thats already incased it makes the relay judder for several seconds ...even if I adjust the hysteresis. But it seems to work fine with one that isnt incased!
 

SgtWookie

Joined Jul 17, 2007
22,221
The problem with your "juddering" is because you do not have hysteresis in your comparator circuit.

If you would post a schematic diagram of your circuit, we could tell you how to fix it to avoid the "juddering".
 
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