Table of Contents
Advertisement
c. Power sWitching circuit
As the signal from the oscillator is amplified through 07
to 06 to change cu rrent to the transformer T2. it causes
voltage to appear on the base of 05 (one of components
is cut by D 11. so that the transistor 05 begins to per·
form switching operation in synchronization with the
oscillation frequency. As 02 is switched. current is
supplied to the emitter side of the transistor 05. which
produces smoothed voltage through the capacitor Cl
and the coil L2. The circuit composed of D4 and VRl is
the reference voltage for the +5 or + l2V supply. which
is used to control the emitter current flowing to the
transistor 09. The current supplied from 09 is used to
create Tr3 inactive by the delayed Cl and C2 voltages
which supplied from Trl-R2-VR1-D3. It goes high with
deactivation of Tr3.
3. Alarm circuit
(Alarm generation circuit)
G~n------~----~-------1~--~~----~--
Ra
R4
PFD
D2
+sv
When power turns off, the voltage accumulated in Cl
and C2 are supplied to the base of Tr2 via Trl ... and
D3. so that Tr2 is kept active and Tr3 inactive for some-
times after power off.
Timing chart
ON
r - I
---4111------"
'-,---
sw
+5V
I~
,
,
u
11
-----1..---',
,
L,
+-, - - -
PFD
-:~t.-
- 89-
MZ 3500
Advertisement
Table of Contents
