Check the listing for details. Bogen CA10A Call-In Switch Press To Call With SCR Circuit. Condition: New. Listed at 36.50 USD. The Bogen CA10A Call-In Switch Press To Call With SCR Circuit for use with PI35A, SI35 and Multigraphic 11 5B, 2223, 2233 System. This is used as a call-in from classrooms or other staff locations to Bogen’s PI35A and SI35A Intercom Systems, Multi-Graphic© Series 115B, 2223, and 2233 Institutional/School Communication Systems, and Multicom 2000® Administrative Communication Systems. The switch is a two-position, rocker-type, single-pole, normally open switch. When pressed, the switch energizes the corresponding annunciator lamp and the call-in tone at the room selector panel, and maintains this condition after the switch is released and until the call is acknowledged by the operator. This is designed for use with the PI35A, SI35A and MultiGraphic Series 115B/2223/2233 systems. It's SCR holding circuits actuate the annunciator signal and LEDs in Bogen’s SBA-Series room selector panels that [rovide momentary press-to-call.