Tone Generator Card

1A1/SA20003 Natural (Whitish) Handle



Like the processor and unlike the extension or exchange line cards this card should only be installed the top shelf in a specific slot. This slot is just to the left of the processor card.

Main Functions

Generate a 25 Hz ring current for distribution via the backplane to all extension cards.
Generate dial tone (350 Hz & 440 Hz) and supply via speech highways when appropriate.
Generate internal ring(back tone) and supply via speech highways when appropriate.
Generate Number Unobtainable  tone (400 Hz) and supply via speech highways when instructed via processor card
Generate engaged tone (400 Hz)and supply via speech highways when instructed via processor card
Generate warn tone (1400 Hz)and supply via speech highways when instructed via processor card
Provide a balanced termination to a speech highway, for when an extension is not connected to a tone or exchange line or another extension.
Generate internal and external ring cadences, mutiplex them at 125 Khz 

IC2 below generates all the above signals for filtering, mixing and amplification.

Cross point switches


The top pair IC5, IC6 output ring back tone or dial tone to the 20 highways
The middle pair IC9,IC10 output engaged or NU tone to the 20 highways
The bottom pair IC14,IC15 output warn tone and silence? to the 20 highways

Ring Generator A




Ring Generator B




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