White Papers and Guides

White Papers
Beta and Steinhart-Hart Equations Explained
QTI Engineering compares the two equations typically used to interpolate the resistance vs. temperature characteristic of NTC thermistors: the Beta Equation and the Steinhart-Hart Equation.

NTC Thermistors
Have questions about negative temperature coefficient thermistors? In this white paper, QTI engineer Gregg Lavenuta gives an overview of the general properties and features of NTC thermistors.

Thermal Shock Testing
Thermal shock is one of the primary sources of temperature sensor failure in HVAC/R environments. QTI Engineering explains their semi-automated thermal shock testing system and shares the results of tests on QTIP68 and QTSSP temperature sensors from QTI and competitors.

T020/T040 Series Stability
This whitepaper presents two stability tests on T020 and T040 Series thermistors at differing applied bias currents.

T150 Series Stability and Drift
This white paper explains how to calculate thermistor drift over time when exposed to temperatures above 100°C, and features the results of testing the QTI T150 line for drift in high-temperature environments.

Thermistor Performance and Reliability in Freeze/Thaw Applications
QTI Engineering put QTIP68 probes to the test in a refrigeration environment (consisting of repeated cool and defrost cycles), and recorded the performance characteristics over time. They also tested a competitor's IP68-rated sensor, and documented probe response times.


Application Notes
Handling and Soldering Methods for SMD Thermistors
QTI Engineering gives tips for safe handling and soldering of surface mount thermistors.

Wire Bonding to NTC Thermistors
This application note describes the bonding specifications that QTI's NTC gold-terminated thermistors are rated to.

Temperature Measurement and Compensation
This paper gives electrical diagrams to illustrate how to use thermistors in temperature measurement and temperature compensation.

Steinhart-Hart Coefficients for QTI Curves and Resistance Values
A list of coefficients for QTI's R/T curves, for use with the Steinhart-Hart equation.


How-To Guides
Waffle Pack Handling Instructions
Chip thermistors can sometimes be damaged or lost when the waffle pack containing them is opened or closed.  This guide gives tips on how to safely handle the waffle pack and thermistors.

Thermistor Interface with Voltage Comparator
This schematic is helpful when interfacing an NTC thermistor to a voltage comparator.

4-20 mA Temperature Transmitter
Ever wondered how to make a temperature transmitter?  This guide shows you how to put one together.

Computer Interfacing to an NTC Thermistor
This guide walks you through creating an analog-digital converter, and includes code to create a resistance/temperature lookup table in BASIC script.

Linear Thermometer
Learn how to create a linear thermometer using this guide as a reference.

Temperature Controller
Make your own temperature controller using this guide.


Reference Charts
Wire Gauge Information
Use this new reference sheet for information on wire gauge dimension and resistance per foot as well as decimal to fraction equivalents and standard ring lug dimensions.