Re: Looking for Temp and humidity sensors

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>Why *IS* that?  I was dismayed by the price and the restricted function of
>the ADI "Bobcat" line of temperature and humidity sensors.  I see that
>Worthington has some very cheap sensors listed with their ADI, HAI and ELK
>offerings.  I would ideally line to monitor temperature and humidity info
>for perhaps 20 different points in the house, with a wide array of
>temperatures, too (chimney temps, hot water heater, fridge, etc).

The Bobcat temperature node includes a power supply, an RS485 interface, an
ADC chip (I think they use a PIC but it's been a while since I looked inside
one), an enclosure and an LM34 temperature sensor.

The Bobcat humidity node includes all of the above but with a Humirel
humidity sensor replacing the LM34. Humidity sensors are not cheap.

If you try to duplicate the design you will find that you really cannot
build them and sell them through distribution channels for much less than
what ADI charges.

If you already have some type of controller with ADC inputs and a power
supply and a little knowledge you can DIY and save (if you conveniently
ignore the cost of the controller). The cheap sensors need something like an
SECU16 or other controller.

I think your plans are overkill but you should look at some of the one-wire
interfaces which allow you to network lots of relatively inexpensive sensors
(at least for temperature, RH is still not cheap). You still need some type
of controller or PC to make sense of the data.