3-32
CIRCUIT DESCRIPTIONS
3.4.8 BATTERY
CHARGER
-
Introduction
Seo figufG 3.18.
The battery charger consists
of a switched mode power supply and some auxiliary clrculiry.
Whenever the
Scope
Meter
Is connected to the line voltage (via the separ^e power adapter/battery
charger PM6907), the instrument switches
over to line voltage operation automatically. If a NiCd
battery pack Is Installed, the ScopeMeter wilt charge
this If line voltage Is present. Special circuitry
prevents discharge of the batteries when the Instrument Is
not
being
used.
-
Detailed circuit description
See figure 3.18 and circuit diagram
A2c
(figure
1 0.7).
HF Fitter
The input
voltage (between 8V and 20V) first passes MF FILTER Z2501 and is used to diive
a flyback
converter.
POWffi SUPPLY
Figure 3. 16 Schematic diagram
battery charger
Une voitage detection
When the ScopeMeter is operated on line voltage, transistor V2521 will
be
driven
by the (filtered)
Input voltage. The signal MAINVOLTHT will become "low" to indicate that the Instrument is operated
from
the line voltage. The related signal MAINS-D (connector XI
201,
pin
5)
is
connected to the
microprocessor analog input 19. When the signal MAINS-0 Is "high", the microprocessor will
not
switch off the ScopeMeter, as in battery operated mode.
To Next Page
Loading...
