1751978

Information

• Patent Grant
• 1751978

• References
• Source

• Patent Number

  1,751,978

• Date Filed

  Not available

• Date Issued

  Tuesday, March 25, 1930
  94 years ago

• CPC

  • H04Q9/06 - Calling by using amplitude or polarity of dc

• US Classifications

  • 361 - Electricity: electrical systems and devices