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3. Power supply Block DIAGRAM
3-1. Block diagram
1 :
sw
T1
,
,
i~
;:
1---1~------<:J
+12V supply
.~
o
>-+-+-----1
,z
f---i-t--:----'O
'i-5V supply
T2
(Fig. 1)
3-2.
Shown in Fig. 1 is the block diagram of the power supply
circuit. Souce power is first eliminated of noise through
the noise filter, rectified, and it then charges the capacitor
of the filter. When this DC voltage is impressed to the
power switching circuit, it starts to oscillate so as' to
convert the DC voltage into a high frequency AC (20KHz
or more) power, which is rectified through the high
frequency ferrite transformer
(H)
to produce +5V and
+12V supplies.
Both outputs are stabilized by means of
the controller.
As each of outputs is supplied to the
controller, control signal
is
fed back to the primairy side
by the means of the saturable reactor (T2). This control
signal changes the oscillation fiequency by controlling
the switching transistor drive current so as to stabilize
outputs.
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