Temp. resistance probe output linearising method - varies current flowing as function of non-linearity

摘要

The output from a detector such as a thermoresistance is linearised by varying the current flowing through it as a function of the non-linearity. This permits use of the detector on various measuring equipments without scaling problems. A platinum resistance probe (1) is connected in series with a resistor (2) and a transistor (3). The voltage across the probe is measured by an operational amplifier (4) whose output is decreased by the voltage across the resistor at the inverting input of an operational amplifier (5). The output voltage (Vs) is proportional to probe temperature and part is fed back to another operational amplifier (6) with a reference voltage supplied by a potentiometer (7). The voltage across the resistor (2) is algebraically added to the reference voltage to control the transistor thus linearising the output voltage.