Tektronix DM501A User Manual

Introduction
This section of the manual describes the circuits
necessary to display in digital form, the value of an input
voltage, current, resistance or temperature. Refer
to
the
block diagram and the
schematic
diagrams (indicated
by a
diamond) in the
diagram
section for an overall view of
the
DM
501A
operation, including
typical input and output
signal levels.
Voltage
Input Circuits
The
internal-external
(INT-EXT)
front-panel switch
(S4-A and
S4-B, see
Fig.
3-1) is used to select eilherfront-
panel inputs
or
rear-interface
inputs.
In
all functions
except
temperature, the LOW input connects
to the main
board floating ground (LO) through
switches
S4-A and
Sl-M.
A dc voltage
applieu
to
tlie
VCl. i'R.C.'.
jriucclo:
;> /
.os
through
switches Si
C
and to
tiio
top
of
ihe
attenuator
resistor
series
netwo.l,
cr
,i;.;
to.y
r.i ii;
i ,2A,
R1104
(20
Vdc),
R1112B,
mtlJ {2L0
Vdc), mii2C,
R1
1
14
( tOOO Vdc), and R1
1
12D.
The
botlom end
((T,
8)
of
R1112D is connected
to floating giound
tiironqh swiich
S1-E
and
Sl-M.
Theinput signal
a:tOiii:atic .
i'.
seiui ,ed
by
pressing
the
desired range
switch for either 20o
.n'
\
V,
20 V,
200
V,
Oi 1000
V.
Ttic aitccurdcj sign'.:
i nupies
through switches
S1-F, Sl-t), Sl-J, SI
t
,
and
I
tie
signal flows 11m
ugh
R tG
13
(iocaiei I oii Lnrtg; :..n
?]
to the
Analog Convertor (U1601
pin
15)
Ffesis.ni
iV.C'l'j is a
current limiting
compeanent that
pia.ilects
t.>'lGui
fror.;
overload.
In
the ac
voltage function
(see
f
ig.
3-2), swiUdn
S'
-C is
open (depressed position)
and capa.itoi ClluO
ac
couples the
in(v,.it sign.al
to
the
nUeiu
.nioi
. Gai^acitois
Fig.
3-1.
Dc
volts switching.

Tektronix DM501A Specifications

General

Brand	Tektronix
Model	DM501A
Category	Multimeter
Language	English