1738988

Information

• Patent Grant
• 1738988

• References
• Source

• Patent Number

  1,738,988

• Date Filed

  Not available

• Date Issued

  Tuesday, December 10, 1929
  95 years ago

• CPC

  • H04R21/028 - with a fluid as resistance material

• US Classifications

  • 381 - Electrical audio signal processing systems and devices
  • 310 - Electrical generator or motor structure
  • 367 - Communications, electrical: acoustic wave systems and devices