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9
KX-TS2368CAW
4.2.4.
In Use Detector Circuit
4.2.4.1.
Function:
This circuit is designed to automatically provide an LED indication when either one telephone or another telephone which is con-
nected in parallel across the line is engaged.
4.2.4.2.
Circuit Description
Q351 turns ON. Then the DC is converted at T351 (9 pin
+, 8 pin -). Q352 base becomes (High) and Q352 turns ON.
When Q352 is ON, Q351 base becomes (Low) and Q351 turns OFF. And no electric current flows in the collector of Q351.
Thus Q351 starts oscillating.
In this circumstance voltage is generated at T351 (1, 2) as well as T351 (3, 4).
This output voltage is then rectified by D351 and D352, and smoothed by C351, C352 thus supplied to the IN USE circuits of
Line 1 and Line 2 respectively.
• Off hook
When the circuit voltage is less than 18 V (unit and telephone are on-hook).
Telephone Line
Telephone Line
D110 [D111] D506 [D556] OFF R520 [R570] Q506 [Q506] base a low level.
Q506 [Q556] OFF
Q507 [Q557] base a high level.
Q507 [Q557] ON
Q508 [Q560] ON D507 [D557] R821 [R823] LED D803-R [LED D805-R] ON.
• On hook
When the circuit voltage is more than 18 V (unit and telephone are on-hook).
Telephone Line
Telephone Line
D110 [D111] D506 [D556] ON R520 [R570] Q506 [Q506] base a high level.
Q506 [Q556] ON
Q507 [Q557] base a low level.
Q507 [Q557] OFF
Q508 [Q560] OFF LED D803-R [LED D805-R] OFF.
[ ] : in case of Line2
Battery T351 (6) T351 (5) collector of Q351
R351 base of Q351
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