Thermister Coupling System
Inductive coupling of 4 thermistors across a 4-mm air-gap in a centrifuge. Digtal and analog intefaces
The thermister Coupler (TC-4T) is a four-channel inductively coupled power and data transfer system. On the Mobile Ring (rotating) side, up to four (4) thermisters can be connected to the system. Each thermisters sensor is supplied with a +5 V DC reference source connected via a 10 KW precision resistor. The applied voltage is divided by the internal 10 KW precision resister and thermisters resistance. The four sensor voltages are digitized by a 12-bit A to D converter and configured to a digital serial data stream. This data stream is modulated to a FSK signal and transferred via the air gap between the Mobile Ring and the Stationary Ring. In the Stationary Ring, the signal is demodulated and transferred via cable to the Remote Box as a RS 422 level serial data stream. In the Remote Box, the serial data stream is reconstructed using 12-bit D to A converters to the original four analog signals, and supplied to the SCU-connector. Additionally the RS 422 level signal is converted to a PC — compatible RS 232 level signal allowing for the display the four temperature values on the PC — monitor. PC — software is used to display the data. The system is powered with a 24 V DC (+/- 10 %) supply. The supply current is below 150 mA. The DC — supply is changed to AC in the Stationary Ring and then coupled to the Mobile Ring where the voltage is rectified to supply the sensors and electronics with power.