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24 NORMAL CIRCUIT OPERATION (BASE UNIT)
24.1. TELEPHONE LINE INTERFACE
24.1.1. Circuit Operation:
24.1.2. ON HOOK
Q102 is open; it is connected for cutting the DC loop current and to cut the voice signal. The unit is consequently in an ON-HOOK
condition.
condition.
24.1.3. SPECIFICATIONS
In the ON-HOOK state (idle), the telephone line current flows as follows: A
→
L101
→
R101
→
C101
→
Q101 B
→
Q101 E
→
C102
→
R102
→
L102
→
PO1
→
B The 48V DC component is blocked by C101, C102, thereby providing an ON-HOOK condition.
24.2. TELEPHONE MODE OPERATION
24.2.1. When a ring signal enters from the Line
1. The ring detection circuit (Transistor Q101) begins to operate,so Q101 is active mode, thus input signal to the BELL pin 1 of the
IC201 (CPU).
2. To the arrival of ring signal to the handset, Pin 12 of IC201(Tx POWER) becomes low and Tx power is turned on. Then IC201
outputs the ring data signal form Pin 10 (Tx data) and it is transmit to the handset.
3. Upon receiving the ring data, and the handset is switched from standby to the talk mode, the base unit receives the modulated
data from the handset, which in cludes the information that the handset becomes from Standby to Talk. This data is then
demodulated at the base unit and passes through a data signal amplifier of IC801. This signal is then input to Pin of IC201.
When the codes coincide, Pin of IC201 becomes a HIGH voltage level. At this time, the transmit condition is enabled and the
transistor Q103 is turned on.
demodulated at the base unit and passes through a data signal amplifier of IC801. This signal is then input to Pin of IC201.
When the codes coincide, Pin of IC201 becomes a HIGH voltage level. At this time, the transmit condition is enabled and the
transistor Q103 is turned on.
24.2.2. Circuit-making from the handset
1. When the operator of the handset presses the talk button, data is transmitted to the base unit. This data is then demodulated
by the base unit and passed through data signal amplifier of IC801 and enters Pin 7 of IC201(CPU).
2. When the codes coincide, Pin 3 of IC201 becomes a HIGH voltage level. At this time,the transmit condition is enabled and the
transistor Q103 is turned on.
3. Pin 23 of IC201 becomes HIGH (HIGH level voltage) and the IN USE LED LED201 is on.
37
KX-TC1005RUC / KX-TC1005RUB / KX-TC1005RUW
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