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From: bill@thd.tv.tek.com (William K. McFadden)
Newsgroups: sci.electronics
Subject: Re: Temperature Probes
Message-ID: <9261@sail.LABS.TEK.COM>
Date: 3 Apr 91 00:23:23 GMT
Sender: root@sail.LABS.TEK.COM
Organization: Tektronix TV Products
Lines: 30
Originator: bill@thd


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"