I'm finally getting round to putting together a temperature (and hopefully humidty) monitoring system for my servers. I am using a neat little kit from http://www.qkits.com/serv/qkits/diy/pages/QK145.asp which gives you the ability to attach four separate DS1820 sensors via a COM port.

I've built the kit sucessfully, only took me half an hour despite the fact I haven't soldered for 10 years.

I'm trying to come up with a sensible way to attach the DS1820 ICs though. They will be on the end of a run of CAT5 cable.

At the moment I have one wired up to test the kit like this:



Please try to ignore the quality of the soldering, I can do better on these joints if I take my time...

I was planning to heat shrink wrap the individual joints and then heat shrink wrap the whole package. The question is, am I asking for trouble ? Am I going to end up with failing joints in six months time ? Is there a better way ?

Not being an expert, it would seem to me that it would make sense to use a very small PC board with four traces each connecting a pair of throughholes. That way, after you clip the excess leads, you don't even have the possibility of wires touching each other. Plus, it might give you a mounting surface.

Edit: Or is it three? Those shadows are confusing me.

The pins themselves will break off from fiddling and flexing before your solder joints fail. That's what you have to be careful of.

Usually an IC like that would be soldered to a circuit board to prevent that problem, and the cat5 would go into an actual RJ45 plug. But as long as you're careful not to break the pins, there's nothing wrong with doing it that way either.

Just grab some veroboard from Maplin and cut it to a two by three piece and solder the wire and sensor in place, it should work a treat. You could then even heat shrink around the board and make it nice and neat!

As long as the solder joints are good, then heatshink will do wonders for you. That bottom joint looks a bit dodgy, can't tell much about the other 2. People have been using the heatshrink method for years with thermistors.. Once the outer sheath is on you aren't likely to end up with failing joints or broken leads due to flexing, unless you deliberately try to flex it. If you're worried, then you could extend the sheath over the bottom third, or even the whole sensor - but you'll lose some time response dues to the insulating property of the heatshrink. Doesn't sound like your application has a need for 1 second response times though.

That bottom joint looks a bit dodgy, can't tell much about the other 2.

Yeah, the other two are much better. In my defence I did all those joints (including pre-tinning the wires and leads) in 90 seconds or so, as ever I was in a hurry to see if it worked...

I need to get something to hold the leads and wires together when I do it properly as I only have two hands.

Doesn't sound like your application has a need for 1 second response times though.

Indeed my script for MTRG will only be taking a reading every five minutes.