US2264696A

US2264696A - Switch control circuit

Info

Publication number: US2264696A
Application number: US275691A
Authority: US
Inventors: Jackson Herbert
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1938-05-26
Filing date: 1939-05-25
Publication date: 1941-12-02
Anticipated expiration: 1958-12-02
Also published as: GB516429A

Abstract

516,429. Electromagnetic relays. JACKSON, H. May 26, 1938, No. 15684. [Class 38 (v)] In a relay system suitable for connecting a radio receiver to A.C. mains 4 when any one of a number switches 9 situated at loud speakers is operated, the switches 9 are adapted to impose or remove a short-circuit from a rectifier 5 which is connected across a winding 2 of a relay, and the winding 2 acts as the secondary of a transformer the primary 1 of which is continuously energized by the A.C. supply 4. In the form shown the rectifier 5 is normally short-circuited and the winding 1 is unable to operate the relay. Opening of a switch 9 causes direct current to pass through winding 2 and the relay operates to close contacts 3 and connect up the receiver. In a modification the switches 9 are in parallel instead of in series.

Description

Dec. 2, 1941. H. JACKSON 2,264,696

SWITCH CONTROL CIRCUIT Filed May 25, 1959' F AZ'JITJQE-ENEW/QBFVE MINIATURE 3% 4 5 I I z 1 l RECTIFIER l r i 6\| I RELAY/ 70 T0 RAD/055T REMOTE SWITCHING-UNIT /2 REMOTE sw/rcwss .7 7, .MW, INVEN TOR.

HERBERTJACKSON 1 w z BY 7% K ATTORNEY.

Patented Dec. 2, 1941 SWITCH CONTROL CIRCUIT Herbert Jackson, St. Helens, England, assignor to Radio Corporation of America, a corporation of Delaware Application May 25, 1939, Serial No. 275,691 In Great Britain May 26, 1938 7 Claims.

The present invention relates to electro-magnetic relays, and is concerned with relays of the direct current type which are adapted to function reliably on alternating current by using them in conjunction with metal rectifiers.

The method usually employed is to connect the metal rectifier in parallel with the energising coil of the relay and, in consequence, the switch contacts (or, it may be, the contacts of another relay) which open and close the circuit of the relay must necessarily be in direct electrical connection with the alternating current supply. There are many cases in which such direct connection is disadvantageous. For example, if the relay were employed for the remote switching of a radio receiver it is obvious that the remote control wiring would have to be as well insulated and protected as the ordinary house lighting mains. A transformer could, of course, be used, but this would add materially to the cost of the remote switching unit. It is an object of the present invention to provide an arrangement whereby the control circuit of the relay is insulated from the alternating current supply, and which, moreover, works at a voltage low enough to be harmless should faults develop in the control circuit wiring.

According to the invention an electro-magnetic relay possesses two windings insulated from each other, one continuously connected across the alternating current supply, and the other connected to a metal rectifier and control contacts on a manual switch, or another relay.

According to another feature of the invention the winding which is connected to the alternating current supply is positioned near the heelend of the relay core, while the other Winding which is connected to the metal rectifier is positioned near the armature-end of the core.

According to a further feature of the invention the metal rectifier is in parallel with the control contacts and both are connected across the armature-end winding of the relay.

The two preceding paragraphs refer in particular to a preferred embodiment of the invention, and it must be understood that relays could be designed according to the main principle of the invention (as set out in the last paragraph but two above) but with the two windings one over the other and/or the rectifier and control contacts connected in series across the control winding. Moreover, the invention is not limited to any particular design of the magnetic circuit of the relay and of its contact spring assembly, but in order that the invention may .be better understood the following description is given, for example, only, of methods of carrying it into effect employing a relay of the type used extensively in automatic telephone systems and showing how the remote switching of a radio receiver may be effected by the use of the relay.

In the drawing:

Fig. 1 shows one embodiment of the invention,

Fig. 2 shows a modification, and,

Figure 3 illustrates a type of relay which may be used with the arrangements shown in Figures 1 and 2.

The relay is well known and comprises (an L-shaped yoke member L (Figure 3), two windings l and 2 being mounted on a core C parallel to the longer limb of the yoke member, an armature A being pivoted to the yoke member opposite the free end of the core and a spring contact assembly S mounted on the yoke member and adapted to be operated by an extension E of the armature A. In this particular case the disposition of the windings I and 2 is similar to that adopted in the case of the impulse-responding relay on a selector switch, that is to say the winding space is divided into two compartments separated by an insulating spool cheek W, although the two compartments are not necessarily equal in size as is usually the case in impulsing relays. The heel-end winding l is connected across the current supply 4 (Figure 1) and its impedance is high enough to limit the current drain to very small proportions. When intended to provide remote switching facilities for radio receivers already installed, the relay may conveniently be mounted in 'a suitable box together with a metal rectifier 5 which is permanently connected across the armature-end winding 2 of the relay. The ends of the winding are also brought out to two terminals 6 and I on the box for connection to the remote control wires 8 to the positions of the remote loudspeakers LS. The latter are preferably each fitted with a volume control which may operate an on-ofi switch 9 at the minimum volume setting, in the Well-known manner.

Referring to Figure 3, it will be seen that when armature A is contracted switch 3 is opened and switch 3 is closed. It is thus seen that when this arrangement is used with the arrangement shown in Figure 1, only the switch 3 is used through connection of conductors I0 and II as shown in Figure 1 and switch 3 is not used; that is, conductor I2 shown in Figure 3 is not connected to anything.

The wiring of the remote control wires is such that the on-off switches at the various remote points are all connected in series across the armature-end winding 2 of the relay. This series connection is necessary because the off position at each switch corresponds to a closure of the armature-end slug, and thus effectively prevents the relay from operating even though the heelend winding I is connected to the alternating current supply.

Not only, therefore, r

What I claim is:

1. In an arrangement for connecting an electrical appliance to a power supply network, a transformer comprising a primary winding connected to said network and a secondary winding, a rectifier connected across said secondary winding, switching means operable to short-circuit said rectifierand thereby render it inoperative, an

armature positioned adjacent said secondary winding and adapted to be attracted thereby only when said rectifier is in operation, said armature acting as a switching means to connect and disconnect the electrical appliance to said network.

2. The arrangement described in claim 1 wherein said switching means operable to short- 7 circuit the rectifier are located at a point remote When any one, or more, of the remoteiswitches is thrown to the on position the short-circuit is removed, and the rectifier acting in conjunction with the armature-end winding 2, which is functioning like the secondary winding of a transformer, allows the relay to operate and close its make-contacts 3 which connect the radio receiver to the current supply. The heel-end winding I may conveniently be connected to a plug for connection to the current supply, while inside the box the heel-end winding terminals are also connected by the relay make-contacts to a socket on the side of the box adapted to receive the mains plug of theradio receiver.

Fig.2 shows a modification bearing self-explanatory legends. The remote switches 9 are here inparallel. This is accomplished by fitting the relay with break contacts instead of make contacts shown in Fig. 1. When all of the remote switches are off as shown in Figure 2 the relay is operated'and the receiver is off that is, switch 3 is opened. Faulty switches, that is poor contact in the on position, cannot cause the set to be switched on prematurely. The standing power drain from the mains is about 2 watts.

I The metal rectifier is extremely small; they can be merely two discs of inch diameter and 1 inch thick. It can be seen that for the arrangement shown in Figure 2 only the switch 3 of the relay shown in Figure 3 is used and the connection is made through conductors H and I2 corresponding to conductors II and I2 of Figure 2.

Finally it will be realized that the relay and rectifier may be employed to effect the remote switching of any other form of electrical appliance, and their" functioning in every case will .be substantially similar to that above described.

'While I have indicated and described several systems for carrying my invention into effect, it will be apparent to one skilled in the artthat my invention is by no means limited to the particular organizations shown and described, but that many modifications may be made without departing from the scope of my invention, as set forth in the appended claims. I

from said appliance and wherein the appliance is connected to the network so as to be energized when the short-circuit is removed from the recti fier by operation of the remote switching means and disconnected from' the network when the rectifier is short-circuited by operation of the remote switching means. I

3. The arrangement described in claim 1 wherein the appliance through operation of the armature is connected to the network so as to be energized when said rectifier. is short-circuited by the switching means and thereby rendered inoperative and disconnected from the network when the short-circuit is removed by the operation of said switching means. w

4. In an arrangement for connecting an electrical appliance to an alternating current source, a

circuitincluding a control switch for connecting anddisconnectingsaid appliance to the source, a relay comprising a pair of reactively coupled windings, one of said windings being connected across said source, means for, deriving a unidirectional current from the alternating current transferred from the source to the other of said windings through said reactive coupling, said vmeans being arranged so as to cause the unidirectional current to flow through said other winding, means for controlling the operation of 6.. The arrangement described in claim 1 wherein theswitching: means comprises a plurality of selectively operable switching devices,

connected in parallel across the rectifier. '7. The arrangement described in claim 1 wherein theswitching means is operable to shortcircuit both the rectifier and the secondary winding H HERBERT JACKSON.

deriving