US3538481A - Externally switched variable attenuators - Google Patents

Externally switched variable attenuators Download PDF

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Publication number
US3538481A
US3538481A US782313A US3538481DA US3538481A US 3538481 A US3538481 A US 3538481A US 782313 A US782313 A US 782313A US 3538481D A US3538481D A US 3538481DA US 3538481 A US3538481 A US 3538481A
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United States
Prior art keywords
attenuator
cavities
housing
variable attenuators
base
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US782313A
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English (en)
Inventor
Maurice M Fernando
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Singer Co
Original Assignee
Singer Co
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Filing date
Publication date
Application filed by Singer Co filed Critical Singer Co
Application granted granted Critical
Publication of US3538481A publication Critical patent/US3538481A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/24—Frequency- independent attenuators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/24—Frequency- independent attenuators
    • H03H7/25—Frequency- independent attenuators comprising an element controlled by an electric or magnetic variable

Definitions

  • An externally switched variable attenuator having low residual reactance for A.C. frequencies up to 1 mHz. is disclosed.
  • An electrically-conductive cast housing is split along a transverse plane to form a base and a removable cover which, when assembled, provide a plurality of independent parallel-spaced internal cylindrical cavities.
  • a pair of internal parallel ducts are positioned transversely of said cavities, one duct at each of the collective common ends of said cavities and intersect said cavities for communication therewith.
  • a continuous rigid conducting bus is supported in each duct and insulated from the housing.
  • a resistor and a reed switch connected in series circuit relation are supported in axially spaced relation and coaxially within each cavity by rigid conductors secured to each of said busses.
  • a cylindrical winding is associated with each reed switch for magnetic actuation thereof.
  • Each winding is secured in spaced coaxial relation with each reed switch by an insulated coil form which is held clamped within an enlarged end portion of each cavity.
  • AC-DC standards must be rigidly constructed to maintain reproduceable differences. They consist of a non-reactive attenuator and a thermoelement which senses the heating effect of a current and which has only a small difference in output characteristics between DC and AC inputs. To provide a practical range of voltage inputs, the attenuator must be variable so that the thermoelement is always operated near to its rated current for best accuracy.
  • FIG. 1 is an isometric view of a preferred embodiment of the variable attenuator of the subject invention.
  • FIG. 2 is a plan view of the attenuator with the cover partially broken away to reveal the interior.
  • FIG. 3 is a transverse sectional view of the attenuator taken on line 3-3 of FIG. 2.
  • FIG. 4 is a longitudinal sectional view of the attenuator taken substantially on line 44 on FIG. 2.
  • a housing 10 preferably made of cast aluminum is split along a horizontal transverse plane to form a base 11 and a removable cover 12.
  • the housing 10 provides a mechanical shield for the attenuator so that the rigid geometry of the circuit will not be disturbed. It also provides an electrical shield against the adverse influence of extraneous electrical fields with the attenuator circuit contained within.
  • the dividing walls between the cavities are cut away at each end thereof provide transverse internal ducts 15 and 16 which extend to the full length of the housing and interconnect with the cavities at the collective ends thereof as best seen in FIG. 1.
  • Rigid busses 17 and 18 are supported centrally of the respective ducts 15 and 16 on stand-off insulators 19 secured to the base 11 as shown in FIG. 3.
  • each cavity Located in each cavity is a metal film resistor 20 having loads 21 and 22, and a magnetic reed switch 23 having leads 24 and 25.
  • Lead 21 is connected to bus 18 by any suitable means, such as soldering, and lead 24 is similarly connected to bus 17.
  • Leads 22 and 25 are connected together so that the resistor 20 and the reed switch 23 are supported in spaced relation and substantially coaxially of the cavity as shown and solely by the electrical connections described above.
  • an insulated coil form 26 of the flanged bobbin type is held in clamped position between the base 11 and cover 12 within an enlargement of the cavity formed by depressions 13 and 14.
  • a cylindrical winding 27 wound on the form 26 is spaced preferably in coaxial relation with the reed switch 23. Leads 28 from the winding 27 are brought out through suitable apertures 29 in the base 11 for connection to an external switching circuit (not shown).
  • a cylindrical conducting shield 30 may be placed in the coil form 26 between the winding 27 and the reed switch 23 and grounded to the base 11 at screw 31 to stabilize the distributed capacitance.
  • the reed switches 23 associated therewith may be selectively closed to insert any one or combination of resistors 20 in parallel relation between the busses 17 and 18 to control the attenuation furnished thereby.
  • the bus 17 extends through an aperture 32 in the housing 10 where it may be electrically connected through a microswitch 33 to the center conductor 34 of a coaxial connector 35 of conventional type which serves as the input connector.
  • thermoelement 36 may be housed in a separate thermally lagged compartment 37 secured to the housing 10 and connection made to the input heater terminal 38 by means of a lead 39 extending through an aperture 40 in the housing 10 and connected to bus 18 as clearly shown in FIG. 2.
  • thermoelement 36 is conventional and forms no part of this invention, it is shown in relation to the attenuator of this invention to illustrate a typical environment, in which the attenuator is used.
  • apertures 41 may be provided for each cavity in the cover 12 and opposed to the apertures 29 in the base 11 to provide suitable independent ventilation for each of the windings 27.
  • the large thermal mass of the housing 10 provides a substantially constant temperature environment for the attenuator in normal use and the independently supported and spaced relation between the ventilated windings 27 and the reed switches 23 provide good thermal isolation preventing any sudden changes in the environment temperature of the resistors 20.
  • the parallel array of the cavities combined with the rigid coaxial spacing of the circuit elements and switching means therefor, in accordance with the teachings of this invention, provide a compact, thermally stable attenuator of low residual reactance especially suitable for the use in making precise ACDC transfer measurements over a range of AC voltages from 0 to 32 and a frequencies up to l rnHz.
  • a variable attenuator comprising: an electrically conductive housing split along a transverse plane to form a base and a cover which, when assembled, form a plurality of independent internal parallel-spaced cylindrical' cavities, a pair of internal parallel ducts positioned transversely to said cavities, one at each of the collective common ends of said cavities and communicating therewith, a continuous conducting bust supported in each duct and insulated from the housing, a resistor and a reed switch connected in series circuit relation and supported in coaxially spaced relation within each cavity by rigid conductors secured to said busses, a cylindrical winding associated with each reed switch for magnetic actuation thereof, and means supporting said winding in each of said cavities in spaced relation to the associated reed switch.
  • variable attenuator according to claim 1, wherein the means supporting said winding is an insulated flanged bobbin held in clamped position between the base and the cover in each of said cavities.

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  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
  • Switches That Are Operated By Magnetic Or Electric Fields (AREA)
US782313A 1968-12-09 1968-12-09 Externally switched variable attenuators Expired - Lifetime US3538481A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US78231368A 1968-12-09 1968-12-09

Publications (1)

Publication Number Publication Date
US3538481A true US3538481A (en) 1970-11-03

Family

ID=25125654

Family Applications (1)

Application Number Title Priority Date Filing Date
US782313A Expired - Lifetime US3538481A (en) 1968-12-09 1968-12-09 Externally switched variable attenuators

Country Status (4)

Country Link
US (1) US3538481A (enExample)
DE (2) DE6947201U (enExample)
FR (1) FR2025677A1 (enExample)
GB (1) GB1229363A (enExample)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6756869B2 (en) * 2000-02-22 2004-06-29 Omron Corporation Housing for plural relay switches

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004054620A1 (de) 2004-11-11 2006-06-08 Henkel Kgaa Geranonitril-Substitut

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597090A (en) * 1949-05-19 1952-05-20 Daven Company Variable attenuator
US3192493A (en) * 1961-05-24 1965-06-29 Radar Design Corp Variable attenuator

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597090A (en) * 1949-05-19 1952-05-20 Daven Company Variable attenuator
US3192493A (en) * 1961-05-24 1965-06-29 Radar Design Corp Variable attenuator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6756869B2 (en) * 2000-02-22 2004-06-29 Omron Corporation Housing for plural relay switches

Also Published As

Publication number Publication date
FR2025677A1 (enExample) 1970-09-11
DE1961063A1 (de) 1971-01-14
GB1229363A (enExample) 1971-04-21
DE6947201U (de) 1970-08-06

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