Toa EXES-6000, Operating And Troubleshooting

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1-2. Handset to Hands-free Mode
Fig. 23 Main Circuit Activated in Handset to Hands-Free
or Handset to Handset Mode
Assume that in Fig. 23, station A in the handset
mode is connected to station B in the hands-free
mode.
(1) A 40Hz handset mode signal and voice signal
from station A are transmitted to the DL unit
via the LM unit and HW-T.
(2) Only the voice signal is sent out from station
B, which is similarly transmitted to the DL
unit.
(3) The 40Hz handset mode signal from station A
preceeds to 40Hz SIGNAL DETECTOR (A),
and its output level becomes high, while the
voice signal is sent to VOICE SWITCH (A)
through a high-pass filter (HPF).
(4) The voice signal from station B passes
through HPF and proceeds to VOICE SWITCH
(B). Since no 40Hz signal is sent out from
station B, the output level of 40Hz SIGNAL
DETECTOR (B) is kept low. The status of logic
elements after this stage is shown in Fig. 24.
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