Universal single point liquid level sensor

Patent · Tue Oct 27 04:00:00 EST 1992

OSTI ID:7117659

Kronberg, J W

A liquid level detector comprises a thermistor and circuitry for determining electrically if the thermistor is wet or dry and additionally, and continuously, if the thermistor is open or shorted. The voltage across the thermistor is filtered to remove low frequency electrical noise, then compared with a reference low voltage to determine if shorted and to a transition voltage chosen to be between the thermistor's normal wet and dry voltages to determine if the thermistor is wet or dry. The voltage is also compared to the supply voltage using a CMOS gate circuit element to determine if the thermistor is open. The gate passes both faults on to an LED to signal that a fault condition exists or indicates by another LED the wet or dry condition of the thermistor. A pump may be activated through a relay if the thermistor tests wet or dry, as desired. 1 figure.

• DOE Contract Number: AC09-76SR00001
• Assignee: PTO; EDB-94-090522
• Patent Number(s): A; US 5159318
• Application Number: PPN: US 7-598302
• OSTI ID: 7117659
• Country of Publication: United States
• Language: English

Related Subjects

440800* -- Miscellaneous Instrumentation-- (1990-)
47 OTHER INSTRUMENTATION
DESIGN
ELECTRONIC CIRCUITS
GATING CIRCUITS
LEVEL INDICATORS
LIGHT EMITTING DIODES
MEASURING INSTRUMENTS
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
THERMISTORS