HP 3457A - 8-18. DETAILED THEORY OF OPERATION; 8-19. Input Circuitry

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FRONT PANEL
DISPLAY
CONTAOL
(PUSHBUTTONS)
Figure 8-1. Multimeter Block Diagram
8-18. DETAILED THEORY OF OPERATION
The
following
sections
give
a
detailed
description
of
the
operating
circuitry
in
the
HP
3457A
Multimeter.
The
circuitry
is
explained
as
follows:
. Input Circuitry
. Ohms Current Source
. A/D Converter
. A/D Controller
. Main Controller
. AC to DC Converter
IMOADD>
Refer
to
schematic
A2/1
for
the
following
discussion.
8-19.
Input
Circuitry
The
purpose
of
the
Input
Circuitry
is
to
condition
the
input
signals
to
provide
full
scale
10Y
DC
input
voltages
to
the
A/D
Converter
during
full
scale
inputs
to
the
multimeter.
The
input
circuitry
can
be
separated
(and
is
explained)
as
follows:
HP 3457A Multimeter
8-5