HP 4262A User Manual

A11
BOARD
CIRCUIT
DESCRIPTION.
The
Wien
bridge
oscillator
frequency
is
derived
from
the
equation:
1/(27y/'RaRbC8C9).
Associated
resistances
Ra
and
Rb
are
selected
from
resistors
R25
through
R30
by
active
switches
Q9
through
Q12
to
set
desired
test
signal
frequency
(both
Ra
and
Rb
have
the
same
value).
The
relationships
of
the
switches
to
the
oscillation
frequency
are
shown
in
the
table
with
the
circuit
diagram.
Automatic
level
control
circuit
Q4
and
Q14
operates
to
maintain
a
constant
oscillator
output
level
against
changes
in
oscillator
circuit
parameters
and
supply
voltage
as
follows:
if
the
oscillator
output
level
rises
above
6.8Vp-p,
Q14
is
turned
on
for
a
longer
period,
the
voltage
across
C12
increases,
and
Q3
is
moved
nearer
to
an
OFF
condition.
Therefore,
the
feedback
to
U3B
increases,
and
the
gain
of
U3B
is
decreased
to
lower
its
output
level
to
the
proper
amplitude.
This
provides
stable
amplitude
charac-
teristics
to
the
oscillator.
The
table
below
shows
the
rela-
tionship
of
selected
source
and
range
resistors
to
4262A
FUNCTION,
CIRCUIT
MODE,
and
RANGE
settings.
At
any
setting,
both
the
range
resistor
Rr
and
source
resistor
Ro
have
the
same
value.
Note
that
the
1009
and
109
source
resis-
tances
include
the
total
series
resistance
of
the
range
resistors
and
the
output
resistance
of
transformers
T1
and
T2.
Table
A.
Range
Resistor
(Rr)
and
Source
Resistor
(Ro)
Selections.
R
ange
1
2
3
4
5
6
7
8
Function
e
120Hz
|
1000pH
|
10.00mH{100.0mH
|
1000mH
|
10.00H
|
100.0H
1000H
sc‘;fi;
1kHz
|
100.0xH|
1000uH
|10.00mH
|100.0mH
|
1000mH|
10.00H
|
100.0H
L
10kHz
|
10.00uH
|
100.04H
|
1000xH
|10.00mH
|100.0mH|
1000mH
|
10.00H
SER
109
1009
1kQ
10k
|
100kQ
RR, Ro
PARA
109
1009
1kQ
10kQ
120Hz
|
1000pF
|
10.00nF
|
100.0nF
|
1000nF
|
10.00uF|
100.0xF
|
1000xF
|10.00mF
S’-‘;‘;l“é
1kHz
|
100.0pF
|
1000pF
|
10.00nF
|
100.0nF
|
1000nF
|
10.00uF
|
100.04F
|
1000uF
C
10kHz
|
10.00pF
|
100.0pF
|
1000pF
{
10.00nF
|
100.0nF|
1000nF
|
10.00#F
|
100.0uF
Re. RolPARA| 100kQ | 10ko 1kQ 1000 100
’
SER
100kQ
|
10k
1kQ
1009
10Q
Full- | 120/
scale
|
1kHz/[1000mQ
|
10.002
|
100.0Q
|
10002
|10.00kQ|
100.0k%
|
1000kQ
|
10.00M
R 10kHz
Re.
Ro
|_SER
109
1000
1k§
10k
|
100kQ
’
PARA
10Q
1009
1kQ
10kQ
|
100kQ
8-48
A
N

HP 4262A Specifications

General

Brand	HP
Model	4262A
Category	Measuring Instruments
Language	English