Philips PM2517X - 3.2.5. Power supply; 3.3.6. Power supply (Fig.26 and S4)

40
3.3.6. Power
supply
(Fig.26
and S)
The instrument
can be
powered
by
4
x 1.5 V batteries
of by a 9 V external
power
supply
(pM
92lg).
ln
the
PM
2517
a stabistor BZX 75
C2Vl is included in
the
input
line of the external
power
input.
The
voltage
supplied
to the
power
circuit is in case of
9
V
external
power
supply
-
7 V.
When the
power
is
switched on,
the
power
circuit will
start oscillating. The oscillating frequency
is:
160
kHz.
The input voltages
are
transferred to
!
+8.5
V
and
=
-8.5
V. The
circuit
js
stabelized with
the feed
back
circuit consisting
of zenerdiode V
850
{BZX
79
C10),
V
852
(BAW
62), supptied to
V
801
(BC
558).
The following
voltages
are measured in
the
power
circuit
oI a
PM
2511
with a
9 V external
power
supplV
P[/]
9218:
ov
ü
I
I
I
l
I
t
t
t
o, Ö
(aNo0E
v
85l
)
-7
5V
-r?
5v
+0
5v
0"0
_9V
ouü
sT25l8
CATNODE
!35I
.t
I
t
l
t
FREOUENCY
v^
160 kBz
NOT'
CHAN6 NG TH€
NPUI VOLTAGE
CIIANG€5 'IiE FREOUENCV
Fig.
.
Dependent
to the function
selected
the supply
voltages
are supplied
via
the function
selecter
to
the integrated
carcuit.
The
current
source
is only
used
in the
iunctions
e
.
oC
ana
*.
The
Rl/S
convertor
is
only
used in
the funcrions
V-
,
(m)Al
.
To
avoid
overloading
the
power
supply
the
LED's in
the PM
2517 E
are directly
supplied
from
the batteries.
q
q
rd
q
q
q
q
t