Envirotech Corporation

Time Computer, Inc.

Robert O Reese

Karl R Wieber

Donald W Garrison

James T Hartman

James A Sholly

In a system for controlling electric power supplied to corona-generating electrodes in an electrostatic precipitator (10), an opacity-sensitive transducer (20) produces an output signal proportional to the opacity of the flue gas exiting from the precipitator (10). The signal from the transducer (20) is compared in comparators (304 and 305) with pre-set upper and lower limits defining a permissible opacity range for the flue gas. When the signal from the transducer (20) exceeds the pre-set upper limit or falls below the pre-set lower limit, automatic voltage controllers (40) are activated to control the power supplied to the corona-generating electrodes in order to restore the flue gas opacity to the permissible opacity range.

Method for controlling electric power supplied to corona generating

An improved precipitator voltage control system including an automatic voltage control (AVC) circuit, a firing circuit, an alarm circuit, a power-saving circuit, a remote set-point control circuit and a power supply, all of which are mounted on a single, readily interchangeable circuit board. The automatic voltage control circuit includes a highly responsive spark detection subcircuit which causes the transformer/rectifier voltage to be reduced to zero at the end of the half-cycle in which a spark occurs and then causes the voltage to remain at zero for a short period of time after which voltage is reapplied in a dual ramp manner causing it to rapidly reach a level below the precipitator arcing potential and then increase at a slower rate to the threshold of sparking. The firing circuit drives silicon-controlled rectifiers (SCRs) through optical couplers which provide several thousand volts of circuit isolation. The alarm circuit detects short-circuit and open-circuit conditions and causes automatic trip-out of the control circuit when such alarm conditions exist. The power-saving circuit allows operation of the precipitator to be monitored and the voltage thereof to be reduced during high resistivity conditions. The remote set-point control allows the drive current to be controlled from a remote source.

Precipitator voltage control system

An improved wristwatch calculator has all of the active circuit elements contained on three chips mounted on the same substrate member in the watch case. A watch chip and a calculator chip each have their outputs connected to a single interface chip consisting of CMOS or I.sup.2 L active elements which multiplex the watch and calculator chip outputs and select the appropriate display as a function of watch mode selection by pushbutton or inertia time demand switches or calculator mode selection by activation of the appropriate calculator keyboard switch on the watch face. The interface chip outputs are connected to six electro-optical display stations.

Wristwatch calculator with interface chip

Disclosed is an analyzer for producing a digital display of the rate of deviation of a solid state wristwatch from a predetermined norm. It comprises a counter and calculator into which are gated a series of high frequency pulses for a period of time dependent upon the operating frequency of the wristwatch time base under test. Included is a keyboard connected by a manual switch to the calculator so that the device may be operated in a calculator mode as well as a clock circuit by means of which the digital display may be used to indicate time.

Growing community of inventors

Lancaster, PA, United States of America

Robert O Reese