Patents by Inventor James A. Stewart

James A. Stewart has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20200116307
    Abstract: A controlled ambient temperature vaporization system including a source of liquid carbon dioxide at a supply pressure, a pressure reduction valve is provided. The system is configured to reduce the liquid carbon dioxide from the supply pressure to a delivery pressure, a heat exchange device. The system is also configured to exchange heat between a stream of ambient temperature air and the carbon dioxide at delivery pressure, thereby producing a vaporized carbon dioxide stream. The system also includes a backpressure regulator, configured to maintain the vaporized carbon dioxide above a minimum delivery pressure.
    Type: Application
    Filed: October 15, 2018
    Publication date: April 16, 2020
    Inventors: Mark Joseph Doore, Gregory Caniglia, James A. Stewart, Eric L. Collinge, Christopher G. WILLIAMS, Andrew Slaugh
  • Publication number: 20200119622
    Abstract: A method for controlling the ambient temperature vaporization of carbon dioxide, including introducing a liquid carbon dioxide stream at a supply pressure into a pressure reduction valve, thereby producing a carbon dioxide stream at a delivery pressure is provided. The method includes introducing the carbon dioxide stream at the delivery pressure into a heat exchange device, thereby exchanging heat between a stream of ambient temperature air and the liquid carbon dioxide stream, thereby producing a vaporized carbon dioxide stream at the delivery pressure, and introducing the vaporized carbon dioxide stream at the delivery pressure into a backpressure regulator, thereby maintaining the vaporized carbon dioxide stream above a minimum delivery pressure.
    Type: Application
    Filed: October 15, 2018
    Publication date: April 16, 2020
    Inventors: Mark Joseph DOORE, Gregory CANIGLIA, James A. STEWART, Eric L. COLLINGE, Christopher G. WILLIAMS, Andrew D. SLAUGH
  • Patent number: 4380687
    Abstract: A control circuit 16 that is responsive to voltage conditions on a cable pair transmission line for selectively disabling a battey charging circuit 12 operating off of line current comprises a resistor R5 and storage capacitor C2 connected in series across the line; a timing capacitor C1 connected between the cathode of a PUT (programmable unijunction transistor) and one wire 32 of the line; and a zener diode D1 between the PUT anode and one wire 32 for establishing a conduction threshold for the PUT. The resistor R5 and primary conduction path of a first bipolar transistor Q2, having its base connected to the PUT anode, are connected in series between the other wire 33 of the line and the charging circuit so that startup current for the charging circuit may be used for charging C2 when the charging circuit is disabled. Means is also included for driving the PUT gate voltage low and turning on the PUT in response to both high and low voltage conditions on the line.
    Type: Grant
    Filed: March 27, 1981
    Date of Patent: April 19, 1983
    Assignee: GTE Automatic Electric Laboratories, Inc.
    Inventor: James A. Stewart
  • Patent number: 4374303
    Abstract: A control circuit 16 that is responsive to voltage conditions on a cable pair transmission line for selectively disabling a battery charging circuit 12 operating off of line current comprises a resistor R5 and storage capacitor C2 connected in series across the line; a timing capacitor C1 connected between the cathode of a PUT (programmable unijunction transistor) and one wire 32 of the line; and a zener diode D1 between the PUT anode and one wire 32 for establishing a conduction threshold for the PUT. The resistor R5 and primary conduction path of a first bipolar transistor Q2, having its base connected to the PUT anode, are connected in series between the other wire 33 of the line and the charging circuit so that startup current for the charging circuit may be used for charging C2 when the charging circuit is disabled. Means is also included for driving the PUT gate voltage low and turning on the PUT in response to both high and low voltage conditions on the line.
    Type: Grant
    Filed: March 27, 1981
    Date of Patent: February 15, 1983
    Assignee: GTE Automatic Electric Laboratories, Inc.
    Inventor: James A. Stewart
  • Patent number: 4158752
    Abstract: The local battery and elements of a booster circuit of the energy storage-energy discharge type of swinging choke power converter are connected in series in the subscriber's local battery loop of a carrier subscriber station terminal. A smoothing capacitor is connected across the battery and booster circuit elements for providing a loop voltage there that may be greater than a local battery voltage where a subscriber Touch-Tone telephone set is off-hook and sending calling signals. Current in the circuit elements is monitored for controlling the duration of the portion of a cycle of operation of the converter during which energy is stored by the choke and, thus, maximum current drain from the battery. In an alternate embodiment, the smoothing capacitor is connected across only circuit elements.
    Type: Grant
    Filed: December 21, 1977
    Date of Patent: June 19, 1979
    Assignee: GTE Automatic Electric Laboratories Incorporated
    Inventor: James A. Stewart
  • Patent number: 4152546
    Abstract: A ringer-power generator circuit is provided in which ring pulses cause positive and negative output voltages of a swinging choke regulator to be alternately connected to one of the tip and ring lines of a handset; and cause a control circuit to be alternately connected to and disconnected from a supply voltage. The control circuit has an RC timing circuit which delays initial turn on of the regulator to prevent bell tapping, and includes a transistor, diodes and timing circuit which control maximum output power and maximum output voltage of the regulator for causing the latter to essentially operate as a voltage limited high impedance source.
    Type: Grant
    Filed: August 25, 1977
    Date of Patent: May 1, 1979
    Assignee: GTE Automatic Electric Laboratories, Inc.
    Inventor: James A. Stewart
  • Patent number: 4145572
    Abstract: In a carrier subscriber terminal, a voltage regulator converts the line voltage to a relatively uniform operating voltage for driving a power converter that charges a local battery. The control circuit for the converter comprises a programmable unijunction transistor (PUT) Q1 having a gate and anode connected to intermediate points of associated pairs of resistors R1-R2 and R3-R4 that are electrically connected across the line, and having a cathode connected through a first capacitor C1 and associated discharge path to one side of the line. A Zener diode D5 is resistively connected across the line to establish a reference voltage which is connected through a first diode D1 to the PUT anode, through second and third diodes D2 and D3 to the PUT gate, and through only the second diode D2 to a second capacitor C2 of the regulator.
    Type: Grant
    Filed: August 26, 1977
    Date of Patent: March 20, 1979
    Assignee: GTE Automatic Electric Laboratories, Inc.
    Inventor: James A. Stewart
  • Patent number: 4127746
    Abstract: In the transmit circuits of one terminal, a high frequency (HF) sinusoidal carrier signal of frequency f.sub.c is combined with a low frequency (LF) pulse signal having a PRF f.sub.p to produce a pulsed carrier signal having a plurality of component frequencies af.sub.c .+-. bf.sub.p. The pulsed carrier is modulated in each voice channel by an associated voice signal to produce sidebands of the HF component frequencies there. A different sideband is selected at HF for each channel by polylithic crystal bandpass filter. The selected HF sidebands are then combined with the carrier signal to translate them to low frequencies for subsequent transmission.
    Type: Grant
    Filed: July 21, 1977
    Date of Patent: November 28, 1978
    Assignee: GTE Automatic Electric Laboratories, Incorporated
    Inventor: James A. Stewart
  • Patent number: 3934089
    Abstract: In a disconnect circuit including a pair of transistor switches that are connected in series between associated lines of a cable pair and a subscriber carrier charging circuit for selectively blocking central office battery line current to the latter during ringing of a physical subscriber handset and when the latter is off hook and is dialing, the capacitor controlling delayed turn-on of the switches is coupled thereto through a capacitive multiplier circuit. A first resistor, Zener diode, and second resistor are connected between the cable pair input sides of the switches. A control transistor is connected between the base electrodes of the switching transistors and one side of the diode. The capacitive multiplier here comprises a pair of transistors connected as a Darlington compound between the capacitor and diode for converting a variable input current to a constant low-level current for charging the capacitor, the multiplier transistors bypassing the remainder of this input current.
    Type: Grant
    Filed: October 31, 1974
    Date of Patent: January 20, 1976
    Assignee: GTE Automatic Electric Laboratories Incorporated
    Inventor: James A. Stewart