1-9. OPERATIONAL MODES AND CONTROLS. (CONT)
OUTGOING CALL WITH MODE SELECTOR SWITCH IN AC SUPV POSITION (CONT)
After the signal passes through ring acknowledge tone detector circuit, the output energizes the 570 Hz integrator circuit. The output of
this circuit is coupled to the timer circuit, which removes the release signal from the send amplifier.
The switching facility which is not receiving a release signal stops sending the 570 Hz release acknowledge signal to the telephone set.
This allows the integrator to return to its normal off condition.
When the integrator switches off, the acknowledge delay circuit also switches off. The acknowledge delay circuit is a transistor in the
timer circuit which is normally conducting. The output of the acknowledge delay circuit supplies the positive voltage necessary for the
tone ringer circuit to function. However, when the integrator and acknowledge delay are off, the tone ringer cannot function for at least
450 milliseconds. After this period of time the telephone set is ready to accept incoming calls.