3835640

Information

• Patent Grant
• 3835640

• References
• Source

• Patent Number

  3,835,640

• Date Filed

  Not available

• Date Issued

  Tuesday, September 17, 1974
  50 years ago

• CPC

  • G04C21/28 - by closing a contact to put into action electro-acoustic means

• US Classifications

  • 368 - Horology: time measuring systems or devices
  • 040 - Card, picture, or sign exhibiting
  • 434 - Education and demonstration
  • 968 - Horology
  • 987 - Organic compounds containing a bi, sb, as, or p atom or containing a metal atom of the 6th to 8th group of the periodic system