• Model #RH- 4
  • ManufacturerFederal Pacific Electric
  • Product TypeN/A
  • MaterialsN/A
  • MarketN/A
  • PeriodN/A


The galvanometer would be connected to a direct phone line and was balanced by a variable resistor at the customer premise. If the current was too high (Alarm Circumvention Attempt) or telephone trouble, the galvanometer would latch the light on.