[sci.electronics] Temperature Probes

whitten@kuhub.cc.ukans.edu (04/01/91)

I've been told that there are temperature probes available which
come in like 8 pin dips with the output already linearized an
such.  Does anyone have any information on the manufacturers of
such a product?
 
Thanks,
Chris

==============================================================================
 WHITTEN@KUHUB.CC.UKANS.EDU              Chris Whittenburg, Univ. of Kansas
 WHITTEN@UKANVAX.bitnet                        Electrical Engineering
==============================================================================

ssave@ole.UUCP (Shailendra Save) (04/02/91)

> temperature probes ...come in like 8 pin dips ...output linearized
> information on the manufacturers of such a product?

  Try National Semiconductor's LM 135, LM335. These are 3pin temp.
  sensors with 10mV/deg variation. They are linear, and are pretty
  accurate. 

					Shailendra
	beaver.cs.washington.edu\!sumax\!ole.uucp\!ssave

bill@thd.tv.tek.com (William K. McFadden) (04/02/91)

Analog Devices and National Semiconductor make some common ones.  My
favorites are the three terminal TO-92 sensors from National that
output directly in degrees F or degrees C (10 mV per C or F, depending
on the part number) with no external components other than a power
source.  Add a component or two, and they can also measure negative
temperatures.

I've been able to buy the cheapest grade of Fahrenheit sensor from
Digi-Key for $2.  Add an 8-pin V to F converter (e.g., LM331), and
you've got a dirt cheap temperature to frequency converter that's ready
to connect to an interrupt line or counter input of a microcontroller.
-- 
Bill McFadden    Tektronix, Inc.  P.O. Box 500  MS 58-639  Beaverton, OR  97077
bill@videovax.tv.tek.com,     {hplabs,uw-beaver,decvax}!tektronix!videovax!bill
Phone: (503) 627-6920                 "SCUD: Shoots Crooked, Usually Destroyed"

bill@thd.tv.tek.com (William K. McFadden) (04/03/91)

I write:
>I've been able to buy the cheapest grade of Fahrenheit sensor from
>Digi-Key for $2.  Add an 8-pin V to F converter (e.g., LM331), and
>you've got a dirt cheap temperature to frequency converter that's ready
>to connect to an interrupt line or counter input of a microcontroller.

As a followup, Digi-key sells the following sensors from National
Semiconductor:

		Accuracy		Temperature			Price
Part	typ@25C/max@25C/max over temp	Range		Package		Each

LM34CH	+/- 0.8F / 2.0F / 4.0F		-40F to +230F	TO-46		14.37
LM34CZ	+/- 0.8F / 2.0F / 4.0F		-40F to +230F	TO-92		 7.20
LM34DZ	+/- 1.2F / 3.0F / 4.0F		+32F to +212F	TO-92		 2.04
LM35CH	+/- 0.4C / 1.0C / 2.0C		-40C to +110C	TO-46		14.34
LM35CZ	+/- 0.4C / 1.0C / 2.0C		-40C to +110C	TO-92		 7.77
LM35DZ	+/- 0.6C / 1.5C / 2.0C		  0C to +100C	TO-92		 2.34

LM331N	Voltage to Frequency Converter			DIP8		 7.50

These are the 3-terminal sensors I was talking about.  The number for
Digi-Key is 800-344-4539.  The data sheets are in the National
Semiconductor Data Acquisition Linear Devices Databook.  Digi-key also
sells:
-- 
Bill McFadden    Tektronix, Inc.  P.O. Box 500  MS 58-639  Beaverton, OR  97077
bill@videovax.tv.tek.com,     {hplabs,uw-beaver,decvax}!tektronix!videovax!bill
Phone: (503) 627-6920                 "SCUD: Shoots Crooked, Usually Destroyed"

ken@csis.dit.csiro.au (Ken Yap) (04/04/91)

While we are on temperature probes, has anybody dissected one of those
cheap digital indoor/outdoor thermometers made by Micronta and sold by
Radio Shack, but probably sold under many other brand names? I notice
that the PCB has contacts for additional buttons. Two seem to be for
min and max readings. I've also seen an ad for model that has serial
output. So it would seem that the chip used has "unadvertised
features".  Anybody know what the extras are and how to get them?

bc338569@longs.LANCE.ColoState.Edu (Brian Catlin) (04/05/91)

In article <1991Apr4.003110.4141@csis.dit.csiro.au> ken@csis.dit.csiro.au (Ken Yap) writes:
>While we are on temperature probes, has anybody dissected one of those
>cheap digital indoor/outdoor thermometers made by Micronta and sold by
>Radio Shack, but probably sold under many other brand names? I notice
>that the PCB has contacts for additional buttons. Two seem to be for
>min and max readings.

  I've taken several of these apart.  If I can remember right, it has sixteen
  pins on it.  These pins are ground, positive, high temp, low temp, memory,
  alarm on/off, high temp out, low temp out, alarm out, set alarm, piezo buzzer
  out, C/F select, and some others that I can't seem to remember.

  We use these to run fans and heaters in our greenhouses and they are pretty
  good for this.  They not only have min/max temperature memories, but they
  also have alarm outputs that can run LEDs or relays to run larger loads.
  The piezo buzzer output connects to (you guessed it) a piezo buzzer.  This
  buzzer sounds any time either the min or the max alarm temperature is reached.
  It comes with a small paper that shows all of the connections and it shows
  how to add LEDs to the three outputs.  Sorry, no serial outputs though.

  Hope this helps!

  B. J. Catlin

  bc338569@longs.lance.colostate.edu