HP 5300A - 5310 A Battery Pack

Model 5300A
Theory of Operation
4-69. During time T2, A2C4 cannot charge, since cur-
rent flows through the diode junction of A2Q5 from
the emitter to base 1. During time T1, A2C4 starts to
charge at a rate determined by the current from the
collector of A2Q2. If the regulated +5 V is high, A2Q2
collector current is also high. This causes the charg-
ing rate of A2C4 to be relatively high. When the volt-
age across A2C4 reaches about 12 V, A2Q5 fires and
generates a 6 V, l-microsecond pulse at base 1 of
A2Q5 to terminate time Tl. The greater the +5 V is,
relative to the reference, the faster A2C4 charges and
the sooner this pulse occurs. This shortens time T1
which serves to reduce the output voltages and, thus,
regulation is achieved. This pulse is coupled through
capacitor A2C5 and diode A2CR4 to the base of A2Q7.
This turns A2Q7 on and turns A1Q2 on, pulling the
A1Q2 collector low. This negative excursion is
coupled through capacitor A1C3 which turns the tran-
sistor off and ends time Ti. As A1Q3 turns off, all
secondary voltages of A1T2 reverse. The voltage at
A2R14 is in such a direction that A2Q7 is turned on
through A2R14, after the initial pulse that was
coupled through A2CR4. It is necessary to keep
A2Q7 and A1Q2 conducting during the entire period
of time T2.
4-70. At the end of time T2, when the flux in the core
of transformer A1T2 is zero, the secondary voltages
automatically reverse. This voltage again is coupled
through A2R14 and turns A2Q7 off, which allows
A1Q3 to turn on again, continuing the cycle. Diode
A2CR5 prevents excessive reverse bias across the
base-emitter junction of A1Q3. To ensure that A2Q5
is definitely off, A2C1 couples a negative spike to its
emitter at the beginning of time T1.
4-71. 5310A BATTERY PACK
4-72. The 531GA Battery Pack is an accessory for the
5300A Measuring System. It connects between the
5300A Measuring System Mainframe and any of the
5300
series
plug-ons.
The
batteries
are
sealed
Nickel
Cadmium type which provide about 48-watt hours
capacity
with
a
normal
output
voltage
of
+12
volts.
When the battery pack is locked between the two
halves of the system, all connections are made to
charge the batteries or supply power to the
instrument.
4-73. Typically, a battery use-time greater than 4
hours-per-charge can be expected, depending on the
particular plug-on used. Recharge time for com-
pletely discharged batteries is 18 hours. However, to
achieve full charge in this time the batteries must be
recharged with the mainframe power switch set to
OFF. The 5300A mainframe must be plugged into an
ac source and the battery pack switch set to CHARGE.
4-74. A light-emitting diode on the battery pack front-
panel glows when batteries are nearing the end of
discharge.
4-75. When the batteries are fully charged they
should not be left charging while operating the main-
frame. For optimum long-term battery life the instru-
ment should not be used for more than 10 minutes
after the LOW BATTERY lamp begins to glow.
4-16
4-76.
The
three-position
slide
switch
on
the
front
panel
has
the
following
functions:
a.
BATTERY.
The
-instrument
gets
its
power
from
the
internal
batteries
whether
the
ac
line
cord
is
plugged
in
or
not.
b.
CHARGE.
The
batteries
are
charged
when
the
line
cord
is
plugged
in.
c.
LINE.
The
batteries
are
charged
at
a
trickle-
charge
rate.
This
is
the
normal
position
when
the
batteries
are
fully
charged.
4-77.
In
either
the
LINE
or
CHARGE
position,
with
the
line
cord
plugged
in,
a
power
failure
switches
oper-
ation
to
the
battery
pack
automatically.
Battery
life
will
be
approximately
10%
shorter
than
it
would
be
if
the
front
panel
switch
were
in
BATTERY
position.
The
three
positions
of
the
front
panel
switch
are
used
as
follows:
a. BATTERY. When instrument is used away
from ac line power.
b. CHARGE. When instrument batteries are
charged, regardless of whether the mainframe is used
or not.
c. LINE. For normal operation from the ac
power line.
4-78. The 5310A circuitry can be divided into two
parts.
a. The current regulator for charging the battery.
b. The circuit to indicate when the battery volt-
age is low.
4-79. Transistors A2Q1, A2Q2, and A2Q3 in combi-
nation with A2R2, A2R1 perform the function of a
current
regulator.
Unregulated
voltage
from
the
5300A
mainframe,
which
is
present
whenever
the
line
cord is plugged in, is applied to TOP connector A1P1
(25). In the CHARGE position this voltage is applied to
the current regulator. Normal voltage is about +22
volts; the battery voltage in CHARGE position is
typically +14 volts. The current regulator supplies a
constant current of about .8 Amp, independent of line
voltage
to
the
batteries
when
the
switch
is
in
CHARGE position. A2R2 is the current sample re-
sistor. A2CRI1 prevents base-to-emitter breakdown
of A1Q1 due to current flowing out of the battery
backwards through Al1Q1, when the line power is
turned off.
4-80. A trickle-current of about 10 mA is supplied to
the battery through A2R4 when _ the front-panel
switch
is
set
to
LINE.
Diodes
A2CR4,
A2CR3,
and
light-emitting diode DS1, with resistors A2R3, A2R5
and transistor A2Q4, indicate when battery voltage is
getting low and nearing the end of discharge. A regu-
lated +5.0 volts from the mainframe is supplied to the
emitter
of
A2Q4.
Battery
voltage
is
sent,
through
A2CR2 and A2CR3, to A2Q4 base. When battery