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Title:
WATER-LEVEL DETECTOR OF POSITIVE-CHARACTERISTIC THERMISTOR TYPE
Document Type and Number:
Japanese Patent JPH1030949
Kind Code:
A
Abstract:

To obtain stabilized output voltage in a broad temperature range by using a synthetic resistance circuit network, which is constituted of only resistors containing a negative-characteristic thermistor as a temperature compensating circuit.

A water-level detector has the circuit constitution, wherein a positive- characteristic thermistor THp, a resistor R1 and a semi-fixed resistor VR are connected to a power supply E in sequence in series, a terminal voltage V1 between the positive- characteristic thermistor THp and the resistor R1 is outputted to a synthetic resistance circuit network Rx comprising resistors R2 and R3 and a negative-characteristic thermistor THn, and an output voltage V0 is outputted by a voltage dividing resistor R4. When ambient temperature T is changed, the negative-characteristic thermistor THn, by which the voltage V1 obtained by a current I1 of the positive-characteristic thermistor THp becomes R4.V1/(R4+R) (R; resistance value of negative-characteristic thermistor YHn, R4; voltage dividing resistor with negative-characteristic thermistor THn) so that the output voltage V0 becomes constant, is used. by constituting the temperature compensating circuit by the synthetic resistance circuit network including the negative-characteristic thermistor in this way, the measuring errors caused by the ambient temperature are decreased.


Inventors:
ASAKURA MASAHIRO
SHIBATA HIDEO
SAITO HIROSHI
Application Number:
JP20429696A
Publication Date:
February 03, 1998
Filing Date:
July 15, 1996
Export Citation:
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Assignee:
KURABE IND CO LTD
International Classes:
G01F23/22; G01K1/20; (IPC1-7): G01F23/22; G01K1/20



 
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