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14-5. BUZZER CIRCUIT
CPU
generates
a buzzer
drive signal, of which
frequency is 1700 Hz and output it.
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v
3
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Qo 3917
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14-6. DRAWER / PAPER WINDER
STAMP CIRCUIT
STAMP
IN
IC5
LB1235
STP
RWD
DRA
© RWD signal
from |C1-55pin
(Stay down the PF key)
5v -
14-7. PRINTER CIRCUIT
CHARACTER SELECTIVE CIRCUIT
time, the character selective signal H1 ~
H13
are
the character to its print position.
3,4
Ht
MOTOR DRIVE CIRCUIT
@
— 26—
The printer motor control signal PM is supplied
from the 7 pin of IC1 as active High-level. The
transistor Q5 is turned on by the PM signal, then
the base voltage of Q5 goes low through the
diode D33 and Q5 turned OFF.
When Q5 is off, the motor drive transistor Q2 is
turned ON, and the motor starts rotating.
If the motor voltage is going to over the rated
value, the over current is supplied to the base of
Q6 through the zener diode ZD5.
When Q6 is ON, the Q4 is going to OFF, then Q2
is turned to OFF. When the Q2 is OFF, the motor
voltage
is getting decreased
to the specified
value, which is mainly fixed by the zener voltage
of ZDS5.
When
the motor voltage is getting under the
specified value, the transistor Q2 is turned ON
again and repeated the cycle@~®@. This feed-
back loop makes to regurate the motor voltage
for the security. The capacitor C24 is installed as
to avoid the deviation of this feed-back loop. The
diode D382 is an spike voltage killer.
When
the printer motor control signal PM
is
turned OFF from the IC1, the Q5 becomes OFF
and Q2 is turned OFF.
When Q2 is OFF, the base voltage of Q3 is
getting High by R29 and Q3 is turned ON. When
Q3 is ON, this transistor lose the electricity
generated in the motor itself to the ground rapidly.
And the motor stop rotating.
Q4
A1528
D1825
VPP
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