1590 and 1575 Super-Thermometer Readouts for use with SPRTs and Thermistors - Features

• Accuracy to 4 ppm (0.001°C) or 1 ppm (0.00025°C).
• Bridge-level performance at less than half the cost.
• Accepts 0.25-ohm through 100-ohm SPRTs plus thermistors.
• Includes all temperature functions and stores setups.

Other Features
Super-Thermometers convert resistance to temperature using your choice of ITS-90 or IPTS-68. ITS-90 requires no conversions; just enter your coefficients directly. For IPTS-68 enter R0, ALPHA, DELTA, A4, and C4. Temperature can be converted from IPTS-68 to ITS-90 automatically at your request. Calendar-Van Dusen equations are also provided in an automated mode. 

Thermistor probes are characterized by coefficients of a logarithmic polynomial. Save money and use low-cost, rugged thermistor standards for ±0.001°C accuracy in the low-temperature regions. Other thermometers don’t do all this. 

Measurements can be displayed as temperatures in °C, K, or °F and as resistance in ohms or a ratio of probe resistance to reference resistance. The current source is controllable between 0.001 mA and 15 mA with a resolution of 0.2%. Integration time and digital filtering are programmable to optimize resolution, stability, and response. 

Datalogging and memory functions store measurements, and each thermometer has its own 3.5-inch disc drive for archiving data. The display is a backlit LCD for visual display of information. It has  an RS-232, an IEEE-488, and a parallel printer port. 

These Super-Thermometers are based on DC electronics, thus eliminating the problems with national lab certification for AC bridges and the removal of quadrature interference from AC-heated fixed-point furnaces. Read about the complete Theory of Operation of Hart Super-Thermometers at www.hartscientific.com 
 

Multiplexers
If two channels aren’t enough, add 10 more with a Mighty-Mux featuring Hart’s handy DWF connectors. In fact, add up to 50 more channels to the 1590. 

The Model 2575 provides 10 more channels for use with a 1575. For the 1590, the Model 2590 Mighty-Mux II has a cascading ability that lets you have up to 50 channels by chaining more than one Mux together, and you can now set continuous constant current levels on each channel to avoid self-heating effects. Whatever your application, a Mighty-Mux will make it easier and more efficient. 

Both units have low thermal EMF relays that are hermetically sealed and magnetically shielded. You’re making true four-wire measurements with a floating guard and support for up to 20 mA of drive current. 

Super - Thermometers vs Digital Multimeters
Good eight-and-a-half-digit multimeters might give you accuracy to ±0.005 °C in the resistance measurement. However, DMMs require separate high-stability current sources, and you have to make EMF offsets, worry about a scheme to switch between forward and reverse current during the measurement, and devise a switch to get a second channel for an external standard resistor. 

Once you’ve done all of this, you still have to convert resistance to temperature with tedious manual calculations. 

Super-Thermometers do all of this automatically. 

Super - Thermometers vs Everything Else
There really isn’t anything else to compare to the 1590 and 1575A. No other readout is this easy to use. You’ll be doing calibrations with it the first day you receive it, not the first day after the training program is over.