US2909746A

US2909746A - Electrical resistor assemblies

Info

Publication number: US2909746A
Application number: US550934A
Authority: US
Inventors: Douglass A Young
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1955-12-05
Filing date: 1955-12-05
Publication date: 1959-10-20
Anticipated expiration: 1976-10-20

Description

Oct. 20, 1959 D. A. YOUNG 2,909,746

ELECTRICAL RES ISTOR ASSEMBLIES Oct. 20, 1959 D A, YOUNG 2,909,746

ELECTRICAL RESISTOR ASSEMBLIES Filed Dec. 5, 1955 6 Sheets-Sheet 2 Filed Dec. 5, 1955 6 Sheets-Sheet 3 Get. 20, 1959 D A, YOUNG v 2,909,746

ELECTRICAL RESISTOR ASSEMBLIES Filed Deo. 5, 1955 6 Sheets-Sheet 4 Fig.9.

n? 13T Ils 9| 93 e9 "R203 may 95 2oz |00 97 UIQ, 204

Fig. 8.

IOITVQS Oct. 20, 1959 D, A, YQUNG 2,909,746

ELECTRICAL RESISTOR ASSEMBLIES Filed Dec. 5, 1955 6 Sheets-Sheet 5 n 21 FQ- o- 23 206 205T1 ,[22 FIQH. [29 203 59 Oct. 20, 1959 Filed Dec. 5. 195s Fig.|3.

D. A. YOUNG ELECTRICAL RESISTOR ASSEMBLIES F ig. I5.

6 Sheets-Sheet 6 Fig.l4.

2,909,746; ICC pdtentea oct. 20,1959

ELECTRICAL RnsrsroR Assnmuns Douglass A. Young, Maplewood, NJ., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December '5, 1955, Serial No. 550,934

7 Claims. (Cl. 338-57) This invention relates to electrical resistor assemblies and has particular relation to resistor assemblies for employment in connection with electrical measuring instruments.

In accordance with one yaspect of the invention, an electrical resistor assembly of improved formation is provided which includes a casing structure providing an enclosure for housing electrical resistors of the so-called card-type. Such a resistor comprises a card or plate formed of an insulating material with suitable resistance wire wound thereabout to provide a resistor unit of planar configuration.

The resistor assembly includes a casing structure of three-part formation with the casing parts arranged for interfitting engagement to provide an enclosure for housing one or more card-type resistors. In a preferred embodiment of the invention, the casing structure comprises a hollow shield or cage having opposed open ends which are closed by cover and base members positioned in interiitting engagement with the cage ends. The base member mounts a suitable support plate which carries the card-type resistors in spaced planes transverse to the plane of the base member. The cover member is conveniently detachably secured to the support plate in an operative position.

For the purpose of permitting the dissipation of heat produced in response to energization of the resistors, the casing structtu'e is provided with a plurality of passages located at opposing sides of the casing structure to permit the flow of air through the enclosure provided by the casing structure. A plurality of electroconductive terminals are conveniently supported by the casing structure within the passages to permit the electrical connection of the resistors to associated external circuits.

The resistor assembly permits the provision of a wide range of resistance values. For this purpose each of the resistors is provided with -a pair of terminals each including a deformable portion. The resistors are arranged to permit engagement of the deformable portions of adjacent resistors with one another in response to deformation thereof to permit the connection of a number of the resistors in series circuit relation. The casing structure is arranged to house other circuit components for electrical connection to the associated resistors. In a preferred embodiment of the invention, resilient means are detachably carried by the support plate to bias such components against the base member for maintaining the components in an operative position.

According to a further aspect of the invention, the cardtype resistor assembly includes a casing structure having parts which may be employed to provide a casing structure for housing resistors of the so-called spool-type. Such a resistor comprises an insulating tube with suitable resistance wire wound thereabout to provide a unit of cylindrical configuration. For this purpose, the cover and base members of the card-type resistor assembly are proportioned for interlitting engagement when the cage, support plate and card-type resistors are in a detached condition to form a casing structure providing an enclosure configured to accommodate one or more spooltype resistors.

The base and cover members are arranged when in intertting engagement to provide a casing structure havingv a plurality of passages located at opposing sides of the casing structure. Such passages permit the ow of air through the enclosure provided by the casing structure for the purpose of dissipating heat produced by energiza- 'tion of the spool-type resistors. Suitable electroconductive terminals are conveniently supported by the casing structure in the passages so as to facilitate the electrical connection of the spool-type resistors to associated external circuits. The spool-type resistors are supported by the base member in suitable insulated compartments provided in the base member.

It is, therefore, an object of the invention to provide an electrical resistor assembly of improved construction.

It is another object of the invention to provide an electrical resistor assembly including a plurality of cardtype resistors of improved construction and arrangement.

It is a further object of the invention to provide an electrical resistor assembly including a casing structure of improved formation to permit the dissipation of heat emanating from the resistors.

It is still another object of the invention to provide an electrical resistor assembly including a casing structure which is convertible from one configuration for housing a card-type resistor to another configuration for housing a spool-type resistor.

It is a further object of the invention to provide a spooltype resistor assembly of improved construction.

It is another object of the invention to provide an electrical resistor assembly including a casing structure comprising a hollow cage in interftting engagement with spaced base and cover members to form an enclosure for a card-type resistor mounted by a support member which is detachably secured to thecover and base members.

It is a still further object of the invention to provide an assembly as deiined in the preceding paragraph wherein the base and cover members are arranged for intertting engagement when the cage, support member and card-type resistor are in a detached conditon relative to the base and cover members to provide an enclosure for housing a spool-type resistor.

Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure l is a schematic view illustrating the invention as applied to an electrical measuring instrument;

Fig. 2 is a view in section of a card-type resistor assembly constructed in accordance with the invention;

Fig. 3 is a view in top plan of the assembly of Fig. 2 with par-ts removed;

Fig. 4 is a view taken along the line IV-IV of Fig. 2;

Fig. 5 is a view illustrating a part of the assembly of Fig. 2 in a diierent position;

Fig. 6 is a view simi-lar to Fig. 5 illustrating a part of Fig. 5 in still another position;

Fig. 7 is an exploded view in perspective of the assembly of Fig. 2;

Fig. `8 is a view in bottom plan of a part of the assembly of Fig. 2;

Fig. 9 is a view taken along the line IX--IX of Fig. 8;

Fig. l0 is a view in top plan of an additional part of the assembly of Fig. 2;

Pig. l1 is a View in side elevation of the part of Fig. 10 with parts shown in section; Fig. 12 is a Iview in top plan of a spool-type resistor assembly with parts removed constructed in accordance with the invention;

Fig. 13 is a View front elevation of still another part of the assembly of Fig. 2; i Fig. 14 is a View in elevation of the assembly of Fig. 12 with parts shown in section; and Y Fig. 15 is a view taken along the line XV'-XV of Fig. 14.

Referring to the drawings, there is schematically illustrated in Fig. l a resistor assembly 1 constituting the subject matter of the present invention. The assembly 1 is shown in'association with an electrical measuring instrument such as a voltmeter 3 which is connected across conductors 4 to measure the voltage across a pair of terminals 5. In the particular application illustrated, the assembly 1 is employed to limit the how-of current through the meter 3 to a desired value. However, the assembly 1 may be employed to advantage `in other installations wherein an electrical resistor unit is desired.

' One embodiment of the invention is illustrated in Figs.

2, 3, 4 and 7. As there shown, the assembly 1 includes -a multipart casing structure 7 providing an enclosure 9 yfor housing one or more card-type resistors 11. The structure 7 includes a base member 13 preferably formed of `an insulating material for supporting certain parts of the assembly 1. As illustrated in Figs. 7, 10 and l1 the base member 13 includes a recessed central part providing a base surface 15 intermediate a pair of raised

end parts

17 and 19 having respectively surfaces 20 and 21 lying in a common plane. The member 13 includes further a pair of spaced

parallel walls

22 and 23 at opposing sides of the member 13 whichterminate short of the

end parts

17 and 19. The

walls

22 and 23 project above the surfaces and 21 as viewed in Fig. 2. The member 13 includes further a raised central section 25 of the base surface 15 which extends between the

walls

22 and 23 to define a pair of spaced

compartments

27 and 29.

In order to permit the `mounting of one or more of the resistors 11 an operative position, a suitable support member 31 is provided having the conguration illustrated in Figs. 4, 7 and 13. As best shown in Fig. 13, the member 31 is in the form of an elongated plate constructed of any suitable material having opposed

terminal edges

33 and 35 and opposed side edges 37 and 39. The plate 31 includes a pair of spaced

ears

41 and 43 extendingtfrom the edge 33 and a slot 45 which connnunicates with the edge 33 through a passage 47 for the purpose of permitting detachable mounting of the plate 31 to the base member 13.

As illustrated in Figs. 3 and 4, the plate 31 is positioned with respect to the base member 13 in a plane transverse to the plane of the base surface 15 with the

ears

41 and 43 located within a pair of spaced

slots

49 and 51 of the surface 15 to have the side edges 37 and 39 located within spaced slotsg53`and 55 formed respectively in

projections

57 and 59 of the

end parts

17 and 19. In order to secure the plate 31 to the base member 13, a suitable screw member 61 is positioned to extend through an opening 63 of the base member k13 and the passage 47 of the plate 31 into a threaded cavity of a screw-retaining member or nut `65 which is located within the slot 45 of the plate 31 as best shown in Figs. 4 and 7. The base member 13 includes a pair of

extensions

67 and 69 which project towards each other from side walls of a recess 71 of the raised section 25 as shown in Fig. l0 for the purpose of preventing rotation of the nut 65 about the axis of the screw 61 in response to rotation of the screw.

The casing structure 7 further includes a hollow shield 73 preferably in the form of a cage having a plurality of spaced openings 74 of the surfaces thereof. The cage 73 is positioned with the open end 75 thereof in interiitting engagement with the base member 13 so that the base member effectively closes the open end 75. For this purpose, the base member includes spaced pairs of

projections

76 and 77 which extend from the raised section 25 to form with the

Walls

22 and 23 respectively spaced

grooves

79 and 81 proportioned to receive opposing edges of the end 75 of the cage 73. The remaining edges of the cage end 75 are positioned within slots 83 and 85 formed in the

projections

57 and 59 of the

end parts

17 and 19. With such arrangement, the cage 73 is positioned intermediate the

end parts

17 and 19 with the cage end 75 in a plane spaced from the plane including the

surfaces

20 and 21 in the direction of the length dimension of the cage. It is observed that such spacing provides

passages

87 and 88 of the casing structure adjacent the

end parts

17 and 19 which connect the enclosure formed by the casing structure with the atmosphere. This arrangement permits the dissipation of heat emanating from the resistors 11.

The casing structure 7 includes further a cover member 89 having the configuration illust-rated in Figs. 7, 8 and 9. The cover member 89 is preferably formed of an insulating material and includes a portion 91 having a surface93 with a Yrim portion 95 projecting transversely of the portion 91. The member 89 is positioned in interfitting engagement with the cage 73 to effectively close the open end 96 thereof. For this purpose, the member 89 includes spaced pairs of

projections

97 and 99 which extend from the surface 93 beyond the rim portion 95 as viewed in Figs. 2, 4, 8 and 9 to form with the rim portion 95 spaced

slots

100 and 101 proportioned to receive opposed edges of the open end 96. The member 89 further includes spaced pairs of projections 103 and 105' which form spaced pairs of

grooves

107 and 109 for receiving the remaining edges of the cage end 96.

The support plate 31 is conveniently employed to mount the member 89 in an operative position for closing the cage end 96. For this purpose, the plate 31 includes spaced ears 1113 and 115 which project from the terminal edge to engage spaced

slots

117 and 119 of the surface 93 of the member 89 as best shown in Fig. 4. As shown in Figs. 4 and 7 a resilient plate 121 having recesses 123 and 125 is positioned in a plane transverse to the plane of the plate 31 with the

ears

113 and 115 of the plate 31 projecting through the recesses 123 and 125 of the plate 121. The plate 121 further includes a central opening 127 which is aligned with a notch 129 of the edge 35 of the plate 31 when the

plates

31 and 121 are positioned `as shown in Fig. 4. A screw-retaining member or nut 131 having a threaded body portion 133 terminating in a restricted hollow neck portion 135 is located with the body portion 133 Within the notch 129 to have the neck portion 135 extend through the central opening 127 of the plate 121. The cover member 89 is secured to the plate 31 by means of a suitable screw member 136 which extends through an opening 137 of the member 89 and the neck portion 135 of the nut 131 into threaded engagement with the body portion 133.

In Figs. 2 and 7, a plurality of card-type resistors 11 are shown mounted in spaced planes parallel to the plane of the plate 31 at each side of the plate 31 by means of rods 139 which extend 4through vertically spaced openings 141 of the plate 31 as viewed in Fig. 4. The rods 139 may be secured to the plate 31 as by a staking operation. The resistors 11 are spaced from one another by suitable spacers 145 and are secured in operative position by suitable nuts 143 which threadedly engage threaded end portions of the rods 139. Each of the resistors k11 comprises a suitable card or plate 11a preferably formed of an insulating material with suitable resistance wire 11b wound thereabout with the windings spaced in the direction of the length dimension of the card 11a. The windings may be insulated from one another by a coating of insulating material which is applied Vto the card 11a and resistance wire 11b. It is ob'- served that the resistors 11 are spaced in a direction transverse to a line which connects the passages 87 and 8. VSuch arrangement provides a very effective heat dissipating action.

. As illustrated in Fig. 4, each of the resistors -11 is provided with a pair of

electroconductive terminals

147 and 147a which are secured to the associated cards 11a at diagonally spaced points thereof. As best shown in Fig. 4, the terminals 147 each includes a plurality of spaced

ears

148 and 149 which define a plurality of slots 150 and 151 for receiving the associated resistance wire 11b to permit an elfective terminal connection of the wire 11b. The terminals 147 are secured to the associated cards 11a by deformation of a pair of the

ears

148 and 149 around the edge of the associated card and by deformation of an end portion 157 through an opening -159 of the card. It is observed that each of the terminals 147 is positioned such that a connector portion 161 thereof extends beyond the edge of the associated card. Similar parts of the terminals 147a are represented by the same numerals with the su'lx a.

In order to permit electrical connection of the resistors 11 to an associated external circuit, a plurality of electroconductive terminals 162 are provided as illustrated in Fig. 3. As there shown, four terminals 162 are supported in spaced relation by the base member 13 at each of the

surfaces

20 and 21 of the

end parts

17 and 19. The base member 13 includes a plurality of spaced

projections

179 and 180 at each of the

end parts

17 and 19 for insulating the terminals 162 from one another. Each of the terminals 162 includes spaced

connector portions

163 and 165 with the portions 165 having openings (not shown) for receiving screws 169 which extend into threaded engagement with hexagonal nuts 171 positioned in hexagonal cavities 173 of the

end parts

17 and 19. The terminals 162 are secured to the base member 13 by screws 175 which extend into threaded cavities 176 of the

end parts

17 and 19.

Connections to the resistors 11 and terminals 162 may be eifected in the manner illustrated in Fig. 3. As there shown the resistor 11 located at the left hand side of Fig. 3 is connected to the terminal 162 positioned at the lower left hand corner of Fig. 3 by a conductor 177 having one end secured to the portion 161 of the resistor terminal 147 and the other end secured to the portion 163 of the terminal 162. Connection of the lower left terminal 162 to an external terminal, such as the terminal3a of the meter 3 of Fig. l, is conveniently made by positioning one end of a conductor 174 leading from the terminal 3a of Fig. 1 between the head of the screw 169 and the portion 165 of the lower left terminal 162. It is, observed that the terminals 162 are positioned in the

passages

87 and 88 with the portions 163 thereof within the enclosure formed by the casing structure spaced in a direction parrallel to the direction of spacing of the resistors 11, to have the portions 165 located externally of the enclosure. This arrangement facilitates the making of connections to the resistors 11 and terminals 162.

If desired, the resistors 11 may be electrically con nected to one another to provide a wide range of resistance values. To this end, corresponding ones of the

connector portions

161 and 161a of adjacent ones of the resistors 11 may be bent into engagement with one another as illustrated in Figs. 2 and 3. For example, as shown in Fig. 3, the portion 161a of the first resistor 11 located at the left hand side of Fig. 3 is bent into engagement with the portion 161a of the adjacent second resistor and the portion 161 of the second resistor is in engagement with the portion 161 of the third resistor. In a similar manner, the portion 16111 of the third resistor engages the portion 161a of the fourth resistor which is located adjacent the plate 31. A suitable conductor 181 has one end secured to the portion 161 of the fourth resistor and thev other end secured to the portion 163 of the terminal 162 adjacent the lower left terminal 162. With the arrangement as described, the four resistors 11 located at the left of the plate 31 as viewed in Fig. 3 are connected between adjacent ones of the terminals 162 in series circuit relation.

y For certain applications, it may be desirable'to hous' other circuit components within the enclosure formed by the casing structure of the assembly 1. In Figs. 2 and 3, a pair of components in the form of condensers 185 vof tubular configuration are shown supported by the base member 13 within the'enclosure; In order to secure the condensers 185 in operative positions, a resilient retaining member 189 having the conguration shown in Figs. 2 and 3 is positioned to extend through a slot 191 of the plate 31. Each of the condensers 185 is positioned between the raised section 25 of the base member and a separate one of the end portions of the member 189 in biased engagement with the section 25.

Condensers of various dimensions may be accom- Inodated by the casing structure. For this purpose, the plate 31 includes an additional slot 195 located below the slot 191 as viewed in Fig. 2. The slot 195 is arranged to receive the member 189 for mounting a condenser 197 in an operative position having a diameter which is less than the diameter of one of the condensers 185 as shown in Fig. 5. The member 189 is also effective to mount a pair of the condensers 197 in operative positions if desired. In Fig. 6, the resilient member 189 is shown positioned to extend through the slot 191 to mount but a single condenser having the dimensions of the condenser 185.

A The operations required to assemble the asembly 1 may now be described. `One or more of the resistors 11 may be mounted on the plate 31 as previously described. The nut 131 is next positioned with the body portion 133 within the notch 129 of the plate 31. The plate 121 is then secured to the plate 31 by passing the slots 123 and 125 of the plate 121 over the

ears

113 and 115 of the plate 131 to have the neck portion 135 ofthe nut 131 extend through the opening 127 of the plate 121. The nut 65 is positioned between the

projections

67 and 69 of the base member and the screw member 61 threaded into engagement with the nut 65 to an extent just sufficient to prevent accidental disengagement thereof. The support plate 31 is then positioned with the

ears

41 and 43 within spaced

cavities

199 and 200 of the base surface 15. The plate 31 is then moved toward the

slots

49 and 51 so as to position the nut 65 within the slot 45 of the plate 31 and to position the

ears

41 and 43 within the

slots

49 and 51. The screw 61 is then rotated in a direc` tion for securing the plate 31 to the base member. The desired connections may then be made between the resistors 11 and the terminals 162.

The cage 73 may then be placed over the plate 31 in interfitting engagement with the base member 13 to surround the resistors 11 as previously described. The cover member 89 is then positioned in intertting engagement with the case 73 and the screw member 136 positioned to extend through the opening 137 of the cover member into threaded engagement with the body portion 133 of the nut 131. The base member 13 includes a pair of

cavities

199 and 203 of the

projections

57 and 59 for receiving securing means (not shown) for mounting the assembly 1 to a supporting surface.

According to the present invention, parts of the casing structure which are employed in the card-type assembly 1 may be utilized to provide a casing structure for housing spool-type resistors, For this purpose, the base member 13 and the cover member 89 are proportioned for intertting engagement when the plate 31, the resistors 11 and the cage 73 are in a detached condition relative to the cover and base members to form an enclosure congured for housing one or more spool-type resistors.

Y Figs. 14 and 15 illustrate the base member 13 and cover member 89 in intertting engagement to form an assembly 1a including a casing structure providing an enclosure for housing a pair of spool-

type resistors

200 and 201. For this purpose, the cover member 89 is provided with a pair of

slots

202 and 204 of the rim portion l which are proportioned to receive extensions 2,05, and 206 respectively of the projections 57V and 59 of the base member. It is observed'that with such arrangement, the cover member 89` is supportedV so as to be spaced from the end parts 17' and 19Y of the basey member 13 to form a pair of opposed passages 210 and 2.11 of the casing structure which permit the ow of air through the enclosure.

In Fig. l2, there is illustrated a single spool-type resistor 200 positioned within the compartment 27 Yof the base member such that the axis of extension of the resistor 200 is substantially parallel tothe direction of spacing of the connector portions 163-of the terminals 162. Such arrangement facilitates the connection of the resistor 200 to the portions 163 of the terminals 162. I f desired, a pair of resistors of different length dimensions may be positioned within a single one of the compartments 27 and 2.9 with the terminals of each resistor being connected to a separate pair of the terminals 162. The cover and base members may be secured together as illustrated in Fig. l by means of a threaded screw member 212 which extends through the aligned

openings

1,37 and 63 of the cover and base sections to engage a suitable threaded nut 213.

The invention permits the manufacture and stocking of a minimum number of parts to formV two resistor assemblies of diierent coniiguration providing diierent resistance values. The construction and arrangement of parts of the assemblies 1 and 1a render such assemblies particularly desirable for employment with electrical measuring instruments. Each of the assemblies 1 and 1a may be associated with instruments of various types requiring various resistance values.

For example, the assembly 1 may be associated With various types of voltmeters with one or more of the resistors 11 comiected to provide the desired resistance value. For this purpose a pair of the terminals 162 are required. The assembly 1 may further be employed in connection with multi-element instruments such as two element wattmeters requiring two resistance circuits. For such an application four of the terminals 162 are required.

' Although the invention has been described with reference to certain specific embodiments thereof, numerous modications are possible and it is desired to cover all modiiications falling within the spirit and scope of the invention.

I claim as my invention:

1. In an electrical resistor assembly, a base member, a support plate of planar configuration detachably secured to said base member in a iirst plane transverse to the plane of the base member, a plurality of card-type resistors carried by said plate in spaced second planes parallel to said rst plane at opposing sides of said plate, a hollow shield having opposing open ends, said shield surrounding said resistors with one of said shield ends in intertting engagement with said base member to close said one shield end, a cover member detachably secured to said plate to close the other of said shield ends, said base member, shield and cover member forming an enclosure for said resistors, and a plurality of electroconductive members each including a terminal portion, said base member supporting said electroconductive members with said terminal portions withinrsaid enclosure spaced in the direction of spacing of said second planes to be electrically connected to said resistors.

2. In an electrical resistor assembly, a pair of cardtype resistors positioned in spaced parallel planes, and a pair of electroconductive members carried at diagonally related points of each of said resistors, each of said electroconductive members including a deformable terminal portion, the terminal portions located at corresponding points of said resistors being engageable in response to deformation thereof to permit connection of said resistors in series circuit relation.

3. In an electricalresistor assembly, a base member 5 having a pair of opposing end portions lying in a common rst plane, a support member carried by said base member between said end portions, a plurality of card-type resistors carried by said support member in spaced second planes transverse to said first plane, a hollow shield having opposed open ends, said shield surrounding said resistors with one of said shield ends in intertting engagement with said base member between said end portions,` said base member supporting said one of said shield ends in a third plane spaced from and parallel to said rst plane, a cover member secured to said support member to close the other of said shield ends to provide an enclosure for said resistors, and a separate plurality of electroconductive members carried by said base member at each of said end portions, each plurality of electroconductive members being spaced in the direction of spacing of said' second planes, each of said electroconductive members including a first portion extendinginto said enclosure through the space between said first and third planes to be electrically connected to said resistor units, and a second portion located externally of said 'enclosure to be electrically connected to an associated circuit.

4. In an electrical resistor assembly, a base member including a rst cavity extending therethrough along a line transverse to the plane thereof, a support member, rst securing means including a part projecting through said irst cavity for detachably securing said support member to said base member, a card-type resistor carried by said support member in a plane transverse to the plane of the base member, a hollow shield having opposed open ends, said shield surrounding said resistor in interlitting engagement with said base section to close one of said shield ends, a cover member in interfltting engagement with said shield to close the other of said shield ends, said cover member having a second cavity extending therethrough along a line transverse to the plane thereof, and second securing means including a part projecting through said second cavity for detachably securing said cover member to said support member, said base member, shield and cover member forming an enclosure for said resistor, said base and cove-r members including integral parts proportioned for interv iitting engagement when said support member, resistor, shield and securing means are in a detached condition relative to said base and cover member to form an enclosure for a spool-type resistor of different conguration than said card-type resistor, said first and second cavities being positioned when said base and cover members are in intertting engagement to receive securing means for securing said base and cover members in interfitting engagement.

5. In an electrical resistor assembly, a base section, a support plate having a slot adjacent one end thereof, said support plate being secured to said base section in a first plane transverse to the plane of the base section with said one end engaging said base section, a card-type resistor carried by said support plate in a second plane parallel to said rst plane, a retaining plate having a pair of resilient terminal portions, said retaining plate being positioned within said slot with said terminal portions located on opposing sides of said first plane, a separate electrical circuit component biased into engagement with said base section by each of said terminal portions, and a cover section supported by said support plate to form an enclosure for said resistor and said circuit components, t v

v6. In an electrical impedance assembly, a casing structure including a base member having a pair of end parts spaced by a recessed central part including a raised section delining with said end parts a p air ofvspaced compartments, and a cover member supported by said base member to form with said base member an enclosure including said compartments; said end parts being located externally of said enclosure, a separate impedance member positioned Within each of said compartments, each of said impedance members having a pair of energizable terminals spaced along a line extending transverse to the direction of spacing of said end parts, and a separate plurality of electroconductive members carried by said base member at each of said end parts, each of said electroconductive members including first and second spaced terminal portions, the iirst terminal portions of each plulality of electroconductive members extending into a separate one of said compartments -to be electrically connected to a separate one of said impedance members, the rst terminal portions of each plurality of electroconductive members being spaced in the direction of extension of said lines, the second terminal portions of each plurality of electroconductive members being located externally of said enclosure to be electrically connected to an associated circuit.

. 7. In an electrical resistor assembly, a casing structure including a base member having a pair of opposed end parts spaced by a recessed central part, said base member further including a pair of side walls spaced by said central part terminating short of said end parts, said central part including a raised section connecting said side walls to define with said end parts and side walls a pair of spaced compartments, and a cover member engaging said base member to form with said base member an enclosure communicating with each of said end parts through a separate plurality of spaced passages, a separate spool-type resistor positioned within each of said compartments to extend along axes parallel to the direction of extension of said raised section, and a separate plurality of electroconductive strips carried by said base section at each of said end parts with each strip positioned Within a separate one of said passages, said strips and passages being proportioned to permit the dissipation of heat emanating from said resistors through said passages, each of said electroconductive strips including first and second spaced terminal portions, the rst terminal portion of each plurality of electroconductive strips being positioned within said enclosure adjacent a separate one of said compartments in spaced relation in a direction parallel to said axes to be electrically connected to a separate one of said resistor units, the second terminal portions of each plurality of electroconductive strips being positioned externally of said enclosure to be electrically connected to an associated circuit.

References Cited in the le of this patent UNITED STATES PATENTS 1,373,895 Leonard Apr. 5, 1921 1,374,693 Vernet Apr. 12, 1921 1,745,872 Stickney Feb. 4, 1930 2,022,486 Blakeslee Nov. 26, 1935 2,457,598 Osterheld Dec. 28, 1948 2,628,263 Bulla Feb. 10, 1953 2,811,616 Green Oct. 29, 1957