Conversation - Panasonic Easa-Phone VA-208 Installation Manual

W EXPLANATION OF CIRCUIT OPERATION (KEY TELEPHONE)
1. Conversation
Hand set (Transmitter and Receiver) is connected to T, R line when HSI is [ON] (OFF-HOOK).
T
I,
HSl
+
+
MIC
-
Incoming
Signal
R36
,
R24
R21 R22
08
izC15
: R33
1.1 Receiving
The voice signal input is emitted from receiver via the sequence of:
T, R terminal + HSl
[ONI -+
DBI (Rectifier) + Sink circuit (Provided to maintain conversation quality by
constant current
supply
for various distance condition to the Central Office Exchange) + Tl + Q4 (Receiver
amp.) + R (Receiver).
1.2 Transmitting
Transmission of the voice signal is output to T, R terminal via following sequence:
MfC + Q6 (Transmitter amp.) + Tl -+ DBI + HSI [ON] + T, R terminal.
NOTE: When the transmission voice level is over from specified level, 07 to Q9 (The receiver mute circuit) is
suppress the side tone by 09 [ON,]
.
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