2136345

Information

• Patent Grant
• 2136345

• References
• Source

• Patent Number

  2,136,345

• Date Filed

  Not available

• Date Issued

  Tuesday, November 8, 1938
  86 years ago

• CPC

  • H04M1/738 - Interface circuits for coupling substations to external telephone lines
  • H04R21/023 - with more than one granular chamber

• US Classifications

  • 379 - Telephonic communications
  • 381 - Electrical audio signal processing systems and devices