| 摘要 |
PROBLEM TO BE SOLVED: To provide a water level detection device having high detection reliability and a large use temperature range when detecting a water level in a water storage tank by use of a self-heating type thermistor. SOLUTION: This water level detection device comprises the self-heating type thermistor 1, a water level detecting resistor, 01, a water level detection power source 2, a resistor 3 for an operating point, a comparison means 4, a load drive transistor 5, a load (a water supplying pump) 6, the water storage tank 7, a microcomputer 10, operating point changeover resistors 11-14, an operating point changeover resistor 15 for abnormality detection, operating point switching transistors 21-24, an operating point switching transistor 25 for abnormality detection, an sir temperature thermistor 32, a water temperature thermistor 31 and a delay timer 33.
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