Temperature Signal Conditioners

Temperature signal conditioners receive AC and DC voltages and signal inputs from resistance temperature detectors (RTDs), thermocouples, thermistors, and other sensors. They provide voltage, frequency, and current outputs to devices such as timers, counters, relays, and potentiometers. Temperature signal conditioning devices filter, amplify, and convert analog inputs to digital signals, or to levels suitable for digitization. Devices that include integral sensors or transducers often provide voltage and current excitation. Temperature signal conditioners work with 2, 3, and 4-wire RTDs that are made from a variety of metals and that feature a variety of reference resistances. They can receive signal inputs from thermocouples with or without cold junction compensation, and from thermocouples with types E, J, K, N, T, B, S, R, and W.   

Important specifications for temperature signal conditioners include the number of analog channels and the number of differential channels. When single-ended outputs are available, suppliers often specify the maximum number of analog channel outputs as twice the number of differential outputs. Differential channels, which have two inputs, define the voltage as the signal to process between the two inputs. Other specifications for temperature signal conditioning devices include sampling frequency, accuracy, and filtering. Accuracy, which is represented as a percentage of a full measurement range, depends on factors such as signal conditioning linearity, hysteresis, and temperature. Temperature signal conditioners with integral filters allow some frequencies to pass while attenuating others.

Temperature signal conditioners are available with several form factors. Some mount on integrated circuits (ICs), standard DIN rails, or printed circuit boards (PCBs) that attach to enclosures or plug into computer backplanes. Others bolt into walls, cabinets, enclosures, or panels. Rack-mounted units fit inside a standard 19” telecommunications rack. Modular styles include stackable units that dock in bays, slots, or boxes. Benchtop or freestanding temperature signal conditioning devices often feature full casings or cabinets and integral interfaces.

Some temperature signal conditioners allow users to make adjustments from a local interface such as a front panel, or from a computer interface, touch screen, or remote handheld programmer. Devices with a computer interface are often programmable, networkable, and web-enabled. Application software is used to control or monitor temperature signal conditioning from a supervisory or host computer. User-configurable software and applications that perform mathematical and statistical functions are also available. In terms of computer hardware, temperature signal conditioning devices vary in terms of random access memory (RAM) and data storage capabilities. Some temperature signal conditioners include hard drives and tape drives. Others include floppy disc drives and compact disc drives. Real-time graphing requires a monitor for the display of data as it is collected. 

There are a variety of applications for temperature signal conditioners. For example, environmental applications include groundwater monitoring and pollution measurement. Automotive applications measure factors such as speed and shock. Some temperature signal conditioning devices are designed for marine use, while others meet the strict requirements of aviation, aerospace, or military applications. Temperature signal conditioning devices are also used in seismic applications such as earthquake or volcano research, and in industries such as mining. Other applications for temperature signal conditioners include meteorology, medicine, and biomedicine. Typically, general laboratory and industrial data acquisition systems do not require devices that are hardened against weather, shock, extreme heat, and other unusual conditions.