Thermistor Multivibrator as the Temperature-to-Frequency Converter and as a Bridge for Temperature Measurement

The symmetrical multivibrator, one timing resistor of which is replaced by a network consisting of a thermistor and passive resistors, is analyzed. The circuit represents at the same time a linear temperature-to-frequency (T-f) converter and a multivibrator bridge (MB), both having the same linearity range at any thermistor network configuration. When the balancing state is reached at an inflection point, the sensitivities of the converter and the bridge are the same. The MB has higher sensitivity than the Wheatstone bridge (WB) and can be balanced independently of the inflection point in the wide range. The converter and bridge performances with practical thermistor transducers are analyzed theoretically and numerically.