Tektronix DM505 Instruction Manual page 30

Theory
of
Operalton-DM 505
I
>
to A/D Converter
curred-Wing
reQstance
n
PROTECTOR
~ 1 3 1 2 131412
CR1302
VOLTSlR
OS1410
unknown
ISOURCE
CRf SO1
resistance
+5 V R1304
LOW
tll
R
I
mA
l r c i
2 6 9 2 4
J
Fis
3-1. Simplified diagram ol the ohms converter.
Table 3-1
OHMS CONVERTER SOURCE CURRENT AND
MAXtMUIYI FULLSCALE VOLTAGE
. I
unknown reslstame x
R current setting
resistance
9
unknown resistamce x R range.
%I1201 has 1OX galn.
Swltch
Positions
LO
Sl
LO
n
LO 12
LO R
LO
R
HI
R
HI
n
HI R
HI
R
HI R
Range - - -
200
flc
2 k ~ '
2Q kRG
200 kQc
2000
kRc
200 RE
2 k n
20 kR
200 kR
2000 kR
Current-Setting
Resistance
I Through
Unknown
Resistance
10
kR
10
kn
100 kR
1 MR
10 Mfl
10 kR
10
kn
100
kR
1 Mfl
10 MR
V Across Current
Setting Resistance'
V Across
Unknown
Resistance
(Full-S~ale)~
1 mA
100 PA
10 PA
1 PA
0.1 pA
1 mA
1
m~
100 PA
10 PA
1
PA
10 V
t v
1 V
f V
1 V
10
V
10
v
10 V
10 V
10
V
0 . 2
V
0.2
v
0 . 2 V
0.2 V
0.2
V
0 . 2 V
2 v
2 V
2 V
2 V