Agilent Technologies 34401A Service Manual Page 105

  • Download
  • Add to my manuals
  • Print
  • Page
    / 163
  • Table of contents
  • BOOKMARKS
  • Rated. / 5. Based on customer reviews
Page view 104
AC Circuit
Referring to the schematic shown on page 9-11, the multimeter uses
a true
RMS ac-to-dc converter to measure ac voltages and currents.
The ac-to-dc converter changes the input ac voltage to a dc voltage.
All voltage ranging is performed in the ac circuit so that the input to
the multimeter’s dc circuitry (
AC_OUT) is nominally 2 Vdc for a full scale
ac input. The dc amplifier is always configured for x1 gain in ac functions
(voltage, current, frequency, and period). Relay
K104 connects the ac
circuit to either the
Input HI terminal or to R121, the current function
voltage sense point. Note that the input to the ac circuit may contain a
dc bias from the applied ac signal.
Input coupling capacitor
C301 blocks the dc portion of the input signal.
Only the ac component of the input signal is measured by the multimeter.
The ac circuit voltage ranging comprises two gain stages
U301 and
U305/U312. The voltage gains for each stage are tabulated below.
The 1st stage is a compensated attenuator implementing a gain of x0.2
or x0.002 as selected by
U304A and U304D. Each voltage range has a
unique 50 kHz frequency response correction produced by a
programmable variable capacitor connected across
R304.
Function Range 1st Stage 2nd Stage ADC Input
ACV, Freq,
or Period
ACI
100 mV
1 V
10 V
100 V
700 V
3 A
1 A
x0.2
x0.2
x0.2
x0.002
x0.002
x0.2
x0.2
x100
x10
x1
x10
x1
x10
x100
2 Vdc
2 Vdc
2 Vdc
2 Vdc
1.4 Vdc
0.6 Vdc
2 Vdc
5
Chapter 5 Theory of Operation
AC Circuit
99
Page view 104
1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 162 163

Comments to this Manuals

No comments