Comments on: Projects for the New Place

By: chipsdad

chipsdad — Mon, 02 Feb 2009 17:03:20 +0000

Yes – you would have to calibrate them in-situ. However, they all should have the same temp/resistance characteristics so if you calibrate one prior to connecting it via the phone wires, that should give you a calibration curve – in the zone you are interested in (probably 50 to 90F), you can probably make a straight line conversion. Then, when installed via the phone, the cal will shift slightly – but the curve will remain the same, so a couple of cals compared to a “regular” thermometer (get a good one) should do the trick!

If you get “brand name” thermistors, they may even have resistance/temp curves that will save you the first calibration. In any case, you can probably get it to within 1 degree!

By: Chip

Chip — Sun, 01 Feb 2009 22:38:35 +0000

Now that is a good idea. I think there was some info on reading thermistors in the book that came with the BasicStamp, I’ll check it out. I assume some sort of calibration would be needed once it was in place, since the length of the phone wiring to the thermistor would impact the discharge rate. I don’t know if that would be significant or not.

By: chipsdad

chipsdad — Sun, 01 Feb 2009 18:11:41 +0000

Hey – another way to (cheaply) measure temperature is to use the BasicStamp I gave to you years ago and a bunch of thermistors. You use the RC Time function on the stamp to measure how long a capacitor takes to discharge through the thermistor – since thermistors vary resistance with temperature, the time to discharge is relative to the temperature. They are cheap – two wire devices, so you could still use the extra two wires on the phone line!

Let me know if you need details – I have the references at work on how to make this work!

Also concur on the Dyson!

By: Ryan

Ryan — Fri, 30 Jan 2009 17:10:40 +0000

Get a Dyson. In the long run it will save you money because I went through vacuums every year because the store no longer stocked the bags and then it would cost a lot to ship them from one supplier that was hard to find! Don’t believe in any of the other bagless vacuum cleaners as when you go to empty them, the dust is all loose and flys everywhere! But yes, 5 year warranty on many. Really worth it!