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A zener diode is employed for suppressing the spike voltage that appears when the transistor is turned
OFF. An example of drive circuit is shown in Figure 3-7. In this circuit, a transistor with zener
diode (zener voltage 60~"W) is used between the base and collector.
CN1
+5V
VH(24V)
~
t
u
TR1 2SD2041 (ROHM)
m
CMN ~
ii
Print
Solenoid
ControlSignal
A
r
.-
—-.
TR1
;
\
\
PrintPulse
\
:
u
I :
/ :
/ /
\
b
F
R2
330Q
VH
23V+ VcE(Sat.) of
TR1 =24V
Fig. 3-7
3.5.2
Pre-fire
This operation is the warming up
' -—--
Q
1
GND
~
Print solenoid drive
of printer, in which
circuit (example)
the operation of a needle wire is improved
by applying to it micro vibrations. Pre-fire is executed under the following conditions. Since the
pulse width is short, no print operation takes place.
Operation timing
When power is turned ON
Supply voltage
24VDCf 1.2V
Frequency
900Hz
Pulse width
120 *5/.&s
Count
32
-12-
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