| 摘要 |
<p>A temperature sensor for a system for controlling the temperature of e.g. a building or refrigerator comprises two or more thermistor sensing elements 11A, 11B etc respectively connected in series with first reference resistors 12A, 12B, etc. Each series circuit is connected in parallel and the parallel network is connected in series with a second reference resistor 13. A comparator device 16 is coupled to compare the output of each respective series circuits 11A, 12A; 11B, 12B, etc with a reference input 15 and an output device (OR-gate 18) delivers a control signal. The arrangement is such that the output is related to a weighted average of the temperatures of the various thermistors 11, the weighting being in favour of the warmest thermistor and being dependant upon the values of resistors 12, 13 and upon the temperature difference between the thermistors. So that any failed thermistor is effectively ignored. <IMAGE></p> |
