James Kuo Feng Tseng

US Patent:

55789935, Nov 26, 1996

Filed:

Nov 28, 1994

Appl. No.:

8/345929

Inventors:

Abdul N. Sitabkhan - Arcadia CA
James W. Tseng - La Canada CA

Assignee:

Autronics Corporation - Arcadia CA
Mass Systems Inc. - Baldwin Park CA

International Classification:

G08B 2100

US Classification:

340614

Abstract:

A solid state temperature compensated annunciator is disclosed. The solid state temperature compensated annunciator includes a pressure sensor for measuring a pressure of the fillant within a vessel and a temperature sensor for measuring the temperature of the fillant within the vessel. The solid state temperature compensated annunciator determines a pressure that the vessel would have if the vessel were filled with a predetermined amount of fillant, and compares the measured pressure to the determined pressure. If the measured pressure is below the determined pressure, a warning signal is issued.

US Patent:

41456190, Mar 20, 1979

Filed:

Dec 3, 1976

Appl. No.:

5/747403

Inventors:

James W. Tseng - La Palma CA

Assignee:

Robertshaw Controls Company - Richmond VA

International Classification:

H01H 3518

US Classification:

307118

Abstract:

There is disclosed a capacitance transmitter that is ideally suited for use with a capacitance probe for level, pressure or proximity measurement in which the capacitance of the probe member responds to the sensed physical parameter. The transmitter has only two conductors which furnish the operational voltage and which transmit the output current signal. The transmitter includes a constant base current generator that produces a minimum base current through the two connectors, an oscillator to develop a train of square-wave voltage signals, a multivibrator circuit receiving the square-wave voltage signals and cyclicly applying controlled currents in response thereto to the probe capacitor and to a reference capacitor; a charge rate discriminating circuit receiving charging rate signals from each of the probe and reference capacitors and developing an output current responsive to differences thereof, a feedback circuit from the output of the discriminating circuit to the multivibrator circuit to increase the charging rate of the probe capacitor in response to the output current and a summation circuit receiving the constant base current and the discriminating circuit output current to provide a current signal proportional to the capacitance value of the probe capacitance. Adjustable components are provided in each of the controlled current circuits to permit the fixed adjustability of the zero and the span of the instrument. A transient supression network circuit can also be provided to protect the transmitter.