The Kellogg Switchboard and Supply Co. commenced the design of the Kellogg 1000 Masterphone in 1935. It was based upon Kellogg's largely successful Triad Circuit which had been developed between 1927 and 1930....
CONTINUED FROM PART 2 Red Bar plungers. The red bar also had different plungers, including a clear plastic plunger. Though the vast majority of Red Bars had red plungers for their hookswitch, a limited...
CONTINUED FROM PART 1 There are other issues concerning the Red Bar that you need to be aware of. First, the Red Bar was also used in businesses that needed complex divided and selective ringing circuits so...