Bestech Australia presents the 28208 signal conditioning module, from Precision Filters. This module is an octal thermocouple conditioner, and is a member of the innovative Precision 28000 family of signal conditioners. Applications for this module include static or dynamic temperature measurement, use as a low-level DC or AC filter amplifier, and much more.
The 28208 provides eight channels of conditioning for thermocouples or other DC and AC voltage inputs. It consists of a low-drift programmable differential pre-amplifier, a 3-pole programmable filter and a programmable post-amplifier. Overall gain may be programmed to x1, 10, 100 or 1000. A programmable reserve setting of x1, 10 or 100 is provided for protection against out of band signals. For example, a reserve setting of 100 with a gain of 1000 will program the pre-amplifier to 10 and the post amplifier to 100, allowing the filter to reject out of band energy before all of the gain is applied.
An open thermocouple condition or a channel overload condition is automatically detected and reported to the graphical user interface (GUI) software. These fault conditions are also indicated by front panel LEDs. A 3-pole programmable Bessel filter is provided with cutoff frequency settings of 1, 10 and 100 Hz. The filter may be bypassed to provide wide-band operation.
Additionally, the 28208-1-ITB isothermal block provides a reference junction for a single 28208 card (8-channels). For accurate cold junction compensation, the temperature of the isothermal block must be converted to the voltage generated if the junction is at that temperature. But the relationship between voltage and temperature is non-linear, and this relationship is commonly referred to as “bowing”. A digital temperature sensor on this isothermal block provides an accurate reading of the block temperature, and errors due to bowing are removed by a microcomputer in the signal conditioner which performs the cold junction compensation. Overall reference junction compensation accuracy is better than 0.6 degrees.
A single-ended output stage is standard. This signal conditioning module may be optionally fitted with a differential output.