Comments on: Temperature and Current sensor evaluation for the Home

By: Kelly

Kelly — Wed, 17 Dec 2008 02:37:04 +0000

I do like the LM34s and didn’t realize there was a Kelvin version, which is even better. I chose the thermistors since they SEEM to be fairly accurate, cheap, and all I need is a voltage divider. I’ll probably include some LM34s or LM135s at some point however.

As far as the current sensing goes, I’ll probably build a simple rectifier circuit for each transformer to keep my costs low.

Thanks so much for the input!

By: Toby

Toby — Tue, 16 Dec 2008 18:40:49 +0000

I am a big fan of the LM34. The LM34CAZ is very accurate and easy to use. Sometimes you need a load resistor to help get lower temperatures:

http://www.labjack.com/forums/index.php?showtopic=1040

To read temperatures below zero you can use a battery to get the negative supply shown on Figure 2 of the LM34 datasheet, or you can use the diode trick shown at the bottom of page 6.

Also consider the LM135 which returns Kelvin and thus is good for negative temperatures.

For current consider something that gives you a nice easy RMS value to read. We have used the ESI-695 with our U3/UE9:

http://www.amazon.com/gp/product/B000I17RAM

With the current transformer you are going to have to sample the 60 Hz waveform and then in software find the peak or RMS value.

By: Home-Automation » joliet blog » Blog Archive » 3 Ways To Spend Less On X10 AM466 ...

Wed, 10 Dec 2008 07:15:54 +0000

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