1
Gary Grantland, Attle D Johnson: Paystation monitor circuit to prevent fraudulent use. Palco Telecom, Robert J Black, January 23, 1990: US04896348 (14 worldwide citation)

A paystation circuit that monitors coin battery signals, hookswitch detect signals and initial rate conditions to provide proper reset signals to the totalizer circuit enabling and/or disabling the dial keypad in order to prevent fraudulent paystation usage.


2
Joseph R McGinty, Steven Michael Faes, Gregory Lee Distler, Eugene Gray Heathershaw, Gary Grantland: Coin validation apparatus. QVEX, Gardner Groff Mehrman & Josephic P C, May 1, 2001: US06223877 (11 worldwide citation)

A coin validation mechanism for evaluating coins and the like inserted therein and for validating acceptable coins includes a coin chute defining a coin path and a sensor for evaluating the type of material of which the object in the coin chute is made of. The sensor for evaluating includes a coil s ...


3
William M Wollet, Gary Grantland: Electronic trigger for prepay type telephone paystations. Palco Telecom, Robert J Black, January 29, 1991: US04988860 (11 worldwide citation)

A trigger switch for use in coin operated devices and particularly in telephone paystations consisting of a plurality of parallel channels each including one or more openings through which a light beam passes. Deposit of coins in the appropriate channels blocks one or more light beams passing throug ...


4
Gary Grantland, Eduard F B Boeckmann: Latching relay hold circuit for a telephone instrument. GTE Automatic Electric, Anthony Miologos, Peter Xiarhos, March 6, 1984: US04435622 (7 worldwide citation)

In a hold circuit connectable to a subscriber telephone line, a line voltage storage capacitor is momentarily connected to the subscriber line charging to line potential and providing trigger current to a silicon controlled rectifier. When sufficient trigger current is gained the silicon controlled ...


5
Gary Grantland, Hugh S Montgomery, Eduard F B Boeckmann, Larry A Woodworth: Electronic hold circuit. GTE Automatic Electric, Anthony Miologos, Peter Xiarhos, April 3, 1984: US04440981 (6 worldwide citation)

In a hold circuit connectable to a subscriber telephone line, a silicon controlled rectifier is turned on by a user operated momentary pushbutton connecting the positive side of the line to the hold circuit. A comparator circuit sensing the initial value of the loop voltage, turns on a transistor an ...


6
Gary Grantland, Eduard F B Boeckmann: Latching relay hold release circuit for a telephone instrument. GTE Automatic Electric, Anthony Miologos, Peter Xiarhos, June 12, 1984: US04454385 (6 worldwide citation)

In a hold circuit including a relay normally latched and connecting the hold circuit to a subscriber telephone line, a first hold release circuit outputs a trigger signal to a silicon controlled rectifier turning on the rectifier responsive to a sensed drop in line potential, thereby providing an el ...


7
Gary Grantland, Hugh S Montgomery, Eduard F B Boeckmann, Larry A Woodworth: Electronic hold release circuit. GTE Automatic Electric, Anthony Miologos, Peter Xiarhos, May 8, 1984: US04447674 (4 worldwide citation)

In a hold circuit including a silicon controlled rectifier (SCR) normally turned on and connecting the hold circuit to a subscriber line, a first hold release circuit outputs a trigger signal to a transistor turning off the transistor and disconnecting a line seizing network. A second hold release c ...


8
Gary Grantland: Electronic common switch having an improved receiver mating arrangement. GTE Automatic Electric, Anthony Miologos, Robert J Black, April 10, 1984: US04442322 (4 worldwide citation)

In a telephone substation employing a dual tone multi-frequency signal generator, the common switch functions of disabling the transmitter and muting the receiver are performed by transistor devices responsive to a control signal produced by the signal generator. A bias voltage provided by the trans ...


9
Gary Grantland, Larry A Woodworth: Loudspeaking substation circuit. GTE Automatic Electric Labs, Robert J Black, Anthony Miologos, January 5, 1982: US04309573 (3 worldwide citation)

An improved loudspeaking substation circuit employing a dual-tone multi-frequency signal generator wherein output tone levels are regulated by the substation transmission circuit when operating in either a loudspeaker or handset mode. The circuit further provides for preventing acoustic feedback and ...


10
Gary Grantland: Paystation transmitter ground detect circuitry. Palco Telecom, Robert J Black, April 11, 1989: US04821313 (2 worldwide citation)

A ground detect circuit for use in telephone paystation consisting of a comparator circuit which compares the voltage across a telephone transmitter included in the paystation to prevent users from fraudulent use of the instrument by grounding the handset transmitter to signal the central office tha ...