[time-nuts] Frequency referenced temperature regulator

[Perry Sandeen]

List,

Looking for a stable temperature sensor I first went to YSI.  They have sold their sensor products to.  Measurement Specialties, Inc.

Perusing their site I came upon a Ni1000 SOT temperature sensor.  It is a nickel based unit that has a basic resistance of 1K ohms at 20 degrees C and rising to 1482 ohms at 80 degrees C. .  It has close to a 6 ohm change per degree.  I tried to find one of their distributors without success.

Entering the part number in Google, I found it is also made by ZETEX.  ZETEX calls it an  IC TEMP SENSOR NI1000 SOT23-3.  The Digi-Key catalog as part number is ZNI1000CT ND.  They are $2.77 each.  

The ZETEX data sheet has a nice circuit for a digital thermometer.  

Perhaps a LM 331 precision voltage-to-frequency IC or using a change in a bridge circuit to a varactor on a VCXO might provide the lack of aging problems that exist with a thermistor when precisely trying to obtain a temperature-to-frequency conversion.

>From another site:  DIGI-KEY   Did you know that you can get FREE shipping on your order? Yes, that's correct -- no minimum order fee and no shipping charges.  The "secret" is that you must send them a check or money order by mail. Time-wise, it will add a couple days to get your parts over ordering them via internet or phone -- the time it takes your letter to get to Minnesota.  (See their "terms and conditions" on their website -- they cover themselves for very heavy cheap items.)

Regards,

Perrier