Features

• Reads PRTs/RTDs to ±0.025°C and thermistors to ±0.005°C
• Model 1522 stores multiple data sets totaling 10,000 readings
• INFO-CON connector allows interchangeable use of calibrated probes
• INFO-CON eliminates errors from programming probe data

     The Models 1521 and 1522 are the first standards thermometers to fit into a
battery-powered handheld package. They're as accurate as ±0.005°C!  You'll
only find this level of accuracy in large desktop units that cost three times more.
 It's no wonder we call the 1521 the Little Lord Kelvin of thermometry.

     Fitting easily into your hand and weighing only 1 pound (0.4 kg), these thermometers
can go anywhere.  And when they get there, you can have total confidence in the
accuracy of your measurements.  The 1522 has the power of a full data logger,
with memory to hold 10,000 readings.   

     The 1521 and 1522 read both Pt-25 and Pt-100 RTDs as well as thermistors.
PRTs and RTDs, with their wide temperature ranges and stabilities, have long been
favored as temperature standards. From -200°C to 100°C, the 1521 reads PRTs accurately to
±0.025°C. Even at 800°C these are high-precision readouts, accurate to ±0.1°C.

     Ultra-stable thermistors offer excellent stability and even greater accuracies over a
more narrow range—typically from about -10°C to 110°C. At temperatures below 50°C,
these Handheld Thermometers read thermistors to ±0.005°C. Accuracy at 100°C is ±0.02°C.

     While a small number of handheld thermometers on the market offer 0.01° resolution,
they fail to provide the accuracy necessary for the last digit to be meaningful. Hart’s Handheld
Thermometers let you select resolution from 0.1° to 0.001° and offer the accuracy to support
even 0.001° resolution. 

     Of course, the 1521 and 1522 let you match the exact resistance-versus-temperature characteristics
of an individually calibrated probe. This is true standards thermometry. Hart’s Handheld Thermometers
read ITS-90, Callendar-Van Dusen, or Steinhart-Hart coefficients for maximum system accuracy.
These are real algorithms, not approximating conversion methods or electronic look-up tables. If you
want to use common industrial curves, RTDs can be read using the common DIN 43760 (IEC 751) curve
and thermistors can be read using the YSI 400 curve. 

INFO-CON Connectors 

     Probes attach to the 1521 and 1522 using Hart’s own “INFO-CON” connector. The INFO-CON
(partially based on U.S. Patent 5,857,777) allows you to change the probes you use without requiring
you to reprogram your readout. A memory chip in the INFO-CON stores all the critical information
about your probe, including its serial number, recall date, and calibration constants. 

     When you connect your probe, the 1521 automatically recognizes whether you’re using an RTD
or thermistor and downloads the calibration constants and type of conversion specific to your probe.
It also checks the recall date stored in the INFO-CON to verify it has not expired. To dedicate a single
probe to your readout, disable the password-protected interchangeability function and your thermometer
will read only the probe you specify. 

     Forget entering calibration constants yourself, and don’t worry about the mistakes that can so easily occur
during that process. You don’t even need to select your sensor type. It’s all stored in the INFO-CON.
Just plug in your probe and you’re ready to take readings.  It doesn’t get any easier. 

     Information is loaded into the memory of the INFO-CON by Hart when you purchase a probe or have a
probe recalibrated by Hart. Alternatively, you may load your own information into an INFO-CON through the
Handheld Thermometer or through Model 9934 LogWare. 

     If you’d like to use a Hart Handheld Thermometer with probes you already own, no problem!  
Spare connectors are available.  They easily connect to your probes, and you can program them yourself. 

Model 1521 LLK 

     The 1521 Little Lord Kelvin uses a menu system for convenient access to all functions. Calibration and sensor
programming functions are password protected to help prevent unauthorized access. 

     “Min” and “Max” functions store the lowest and highest readings since the last reset. The “Hold”
function freezes and stores the current reading (up to six may be stored) for later recall. And the “Delta”
function computes the difference between the current reading and a reference value, which may
be recorded at any time. 

     Each thermometer comes complete with rechargeable nickel-metal-hydride batteries, an AC
adapter/charger, an RS-232 cable for connecting to your PC, and a spare INFO-CON connector.  
Every unit also includes a NIST-traceable calibration with actual resistance measurements for your
individual meter at ten point s- four representing typical RTD values and six representing typical thermistor values. 

Model 1522 LLL 

     The Model 1522 Little Lord Logger has all the power and great features of the 1521 plus the ability to log data.  
Two data acquisition modes are included. 

     In “Auto Logging” mode, the 1522 can store up to 10,000 measurements at user-selected
intervals, including the value, unit of measure, date, and time of each measurement.  If you need
more than one data set, stop recording any time and record as many sets as you like up to a total
of 10,000 values. Once the 10,000 value limit is reached, recording stops, so data is never lost unless
you tell the 1522 to clear its log. 

     The 1522 also holds as many as 25 data labels in its memory so that each set of data can
be uniquely tagged.  Simply select one of the 25 labels you’ve created before recording data.  
This label is then recorded with each measurement. 

     In “Demand Logging” mode, up to 100 individual measurements can be recorded, each one tagged with
one of the 25 data labels.  Whether you need a lot of measurements from one source or single
measurements from many sources, the 1522 is a powerful data recording tool. 

     With Hart’s 9934 LogWare software, data management is easy.  Data sets gathered remotely
through the 1522 can be easily downloaded to a PC either as a single file or as individual files for each
data set.  Link the LLL to your PC through a serial cable or its IrDA port to send data as ASCII or binary files.
View the data, graph it, or apply alarms. With LogWare you can record data in real time either from a
1522 or 1521 Thermometer.