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Substation telephone circuit

US 2,137,409 A · Inventors: MARTIN TALBOT G et al.

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Listed from its USPTO record in Patent Yard's full-term archive. Its claims, description and drawings are in the USPTO PDF and on Google Patents, and the Claude kit works from them.

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Why it's free to use

  • Granted November 22, 1938. A patent granted before 1976 lasted at most 17 years from grant, so its term ended by November 22, 1955.
  • We check US rights only. Old patents can still inspire new ones: improvements may be patentable.
FiledNovember 20, 1933
GrantedNovember 22, 1938
Term endedNovember 22, 1955
Application number—
Classification (CPC)H04M15/30 +1 more
Length5 pages

Timeline

Timeline From USPTO dates

19341937194019431946194919521955Application filedNov 20, 1933Patent grantedNov 22, 1938Term endedNov 22, 1955

Sources & verification

Official USPTO records

Full published documentText and every drawing sheet as a PDF.USPTOFile historyStatus, office actions, notices, fee records and petitions.USPTO Patent CenterPatent Public Search recordSearchable full text and bibliographic data.USPTO

Cross-check elsewhere

Google PatentsFull text, worldwide family, citing patents and legal events.patents.google.comJustia PatentsFull text, claims and classification.patents.justia.comFreePatentsOnlineFull text and PDF.freepatentsonline.comEspacenetForeign family and legal status.European Patent Office

Everything on this page comes from the USPTO record linked above.