w:DTMF receiver at a w:No. 5 Crossbar office. Cover removed to show circuit boards. These receivers were used in Originating Registers to support touchtone subscriber dialing. The sealed rectangular relays Z1, Z2, Z3 etc, seen below, converted from the square code of DTMF to the w:two-out-of-five code used throughout w:5XB switch. The round white trimmers set the frequencies and sensitivities of the individual tank circuits. Seen here at The Museum of Communications in Seattle, Washington. June, 2000.
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DTMF receiver at a No. 5 Crossbar office. Cover removed to show circuit boards. These receivers were used in Originating Registers to support touchtone subscriber dialing. Seen here at The Museum of Communications in Seattle, Washington. June, 2000.