US2244058A

US2244058A - Interrupter circuit

Info

Publication number: US2244058A
Application number: US302256A
Authority: US
Inventors: Crofford Daniel Osmund
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1939-10-31
Filing date: 1939-10-31
Publication date: 1941-06-03
Anticipated expiration: 1958-06-03

Description

June 1941- o. o. CROFFORD ,058

INTERRUPTBR CIRCUIT Filed Oct. 31; 1939 INVENTOR z. 0. Croffomi ATTOR NEY M. June' 3, 1941- 2,244, v8

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" closure of the lower contact of relay W: will complete a circuit which will shunt the resistor R: out of the system.

The bridge will remain unbalanced as long as the lamps L1 and In have impedances which are substantially lower than the lmpedances oi the During, the unbalanced condition of the bridge, the relayW: will remain I operated.

However, the shunting of the resistor R3 out of the circuit will cause an increased current to flow from the battery 81 through the various arms of the bridge. The increased current will gradually increase the temperature of the lamps L1 and In and hence their impedances will rise by corresponding amounts. After the impedances of the lamps L1 and In have been raised to values approximating the resistances of elements R1 and R2, the bridge will become halanced and practically no current will then iiow through the winding of the relay W2. Upon the release of the relayWz, the lamp L1 will become extinguished, and at the same time the shunt around resistor R: willbe removed.

The re-connection of the resistor R: to the circuit will then reduce the iiow oi current from the battery B1 through the various arms of the bridge. This will be accompanied by a reduction in the impedances of the lamps L1 and In as the temperatures of their filaments are lowered. The bridge will then become unbalanced and the relay We will, therefore, be re-operated. The lamp In will become re-illuminated, and again the resistor R3 will be shunted out of the circuit. This action will be repeated again and again as long as the relay W1 remains operated.

Thus the relay W1, which may be, for example, the control relay of a ringing circuit used in a telephone system, may be employed to initiate the operation of the circuit illustrated in the drawing. The operation of the relay W1 will cause the lamp L3 to flash automatically at regular and predetermined intervals. These flashes will cease upon the release of relay W1.

Upon the operation of relay W1, the flow of current from battery B1 to the winding of relay W: through the bridge will rise almost immediately to its maximum value. The time required to reach the maximum will be determined only by the inductance of the winding of relay W1. This current is of course due to the unbalance of the bridge. ,As the lamps L1 and L: thereafter heat up, the bridge will approach a balanced condition and the flow of current through the winding of relay W: will be progreswell as by the currents required to operate and release the relay W2. The resistor Ra. which is connected into the circuit upon the release or the relay W2, controls the rate at which the lamps L1 and L: will reach a predetermined high temperature. All of these factors may, oi. course, be adjusted as conditions may require.

The resistor R1 may be any stable resistance. If desired, it may be an adjustable resistance the magnitude 0! which is controlled according to the operation or release of relay W2. The insertion of the resistor R3 into the circuit in effect reduces the eilfective potential applied to the bridge. Moreover, the resistor R: may be replaced by a non-inductive winding mounted on the core of the relay W2. The signal lamp 1o may be replaced by any other indicating device as will be apparent to those skilled in the art.

In one installation, the lamps L1 and Le were of the tungsten filament type and exhibited an impedance of 15 ohms when at room temperature, and approximately 150 ohms when hot. Each of the resistors R1 and R: were of approximately 150 ohms. The battery B1 was a l0-volt battery. These values are given herein merely for illustrative purposes and are not to be construed as limitations on the invention.

It will be understood that the lamps L1 and L: as well as the resistors R1 and R: may, if desired, be enclosed within a single envelope in any well known manner. These elements may be varied in practice to introduce any desired amount of delay between the successive flashes of the lamp L2. By adjusting these elements to different predetermined magnitudes, the periodicity of the pulsating current produced may be changed to any predetermined value.

In accordance with this invention, the lamps L1 and L2 may themselves be the flashing lamps of the circuit. These lamps will flash in step with lamp L3. In such an arrangement the lamp La may be eliminated if so desired.

It lamp L3 is thus eliminated and lamps L1 and In are used as the visual indicators, it will be necessary to adjust the elements of the circuit so that the flow of current through the lamps L1 and L: when relay W: is unoperated will be too small to illuminate these lamps. Upon the operation of relay W2, however, the flow of current through lamps L1 and L2 will be suiiicient to adequately illuminate them. In this arrangement the impedance oi the lamps will be varied over a wide range and the reliability of the circuit will therefore be improved. This arrangement will be especially suitable if the lamps L1 and L2 and resistors R1 and R: are built into a single unit.

While this invention has been shown and described in certain particular arrangements merely for the purpose or illustration, it will be understood that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. An interrupter comprising a Wheatstone bridge arrangement, two 0! the opposite arms of I the bridge including equal non-linear resistors respectively, the other two opposite arms of the bridge including two stable equal resistors, respectively, a source of voltage connected to one of thediagonals of the bridge, a relay the winding of which is connected to the other diagonal or the bridge, and means responsive to the operation of said relay for varying the tlow oi current from said source of voltage.

2. An electrical interrupter comprising tour elements arranged a arms 01' a Wheatstone bridge, two oi the opposite arms of said bridge including equal invariable impedancu, respectively, the other two opposite arms of said bridge including two equal impedances which vary with the ilow oi current therethrough respectively. a source 01' potential connected as a diagonal of said bridge, a translating device connected as the other diagonal of said bridge. and means responsive to the iiow of current through said translating device to vary the eiiective potential of said source.

3. The combination oi two equal stable resistors, two equal non-linear resistors, said iour resistors being arranged as the arms of a Wheatstone bridge, the opposite arms of which are said-two equal stable resistors, a source oi voltageia fli'th resistor connected in series with said source of voltage as one 01 the diagonals oi the bridge, a relay the winding which is connected asthe other diagonal oi the bridge, and means responsive to the operation of said relay for shunting the fifth resistor out of the circuit.

4.-A Wheatstone bridge interrupter circuit comprising two equal tungsten filament lamps which are arranged as oposite arms of the bridge, and two equal stable resistors arranged as the other two opposite arms of the bridge, a relay having its winding arranged as one 01' the diagonals oi the bridge, a source or potential, a variable resistor which is connected along with said source as the other diagonal oi the bridge, and means responsive to the operation 01 the relay for changing the magnitude oi said-variable resistor.

5. An automatic current interrupter comprising two equal non-linear resistors. two equal stable resistors, said four resistors being arranged as the arms of a Wheatstone bridge, a mm resistor connected to one of the bridge diagonals (or controlling the supply oi current to the bridge, a relay the winding of which is coupled to the other 01' the diagonals of the bridge, said relay being operated when the bridge is unbalanced and released when the bridge is balanced, and means responsive to the operation oi said relay for changing the magnitude 01' said fli'th resistor. I

6. A circuit interrupter comprising the combination of a translating device such as a relay which may be operated and released, a source oi potential, a Wheatstone bridge interconnecting said source and said translating device. said Wheatstone bridge having both linear elements and non-linear elements as its arms, said translating device being operated when the bridge is unbalanced and released when the bridge is balanced, and means responsive'to the operation of said translating device to increase the effective potential oi said source so as to increase the .iiow or current through said linear elements and said non-linearelements and to balance the bridge.

DANIEL OSMUND CROFFORD.