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2.2 DC AND AC SENSITIVITY.
With the internal 6-volt supply, one-percent bal-
ances may be easily made up to 10kR and with care
up t o 100kR. Above 100kR a higher external voltage
should be used (paragraph 3.2).
Below
ln,
the sensi-
tivity limits the accuracy t o f l ~ m R . A more sensitive
meter may be placed in series with the internal meter
by plugging it into the BIAS jack on the side of the
bridge.
A 100-a resistor in s e r i e s with the internal 6-V
supply limits the current in the unknown t o 6 0 mA.
The unknown is in s e r i e s with the CGRL rheostat for
external dc, s o that the unknown current is greatest
when the CGRL dial is a t zero.
The maximum power that can be applied to the
bridge by the internal supply is 0.09W; thus there is
nodanger of injuring components rated a t 0.1W or more.
At range extremes it is often desirable t o make
1-kHz a c measurements to increase sensitivity.
For
most resistors, the difference between the measured
1-kHz and dc values is negligible.
An
external tuned null detector, such a s the
1232, is very desirable when making measurements
at frequencies other than 1kHz. It may be connected
between the LOW UNKNOWN terminal and the 1650-B
case. The screw near the UNKNOWN binding post i s
a convenient ground point.
t
I
HELL
L-
l
2
M A X I M U M DC BRIDGE VOLTAGE
A N D CURRENT
2.3 DC VOLTAGE AND CURRENT LIMITS.
WARNING
Bridge voltages must be limited t o pro-
tect the bridge and the unknown com-
ponent from damage.
It is a l s o advis-
able to limit the current t o 5 mA or l e s s
t o protect the operator from injury. T h e
maximum voltage limit, standard EIA
t e s t voltages and some military t e s t
voltages
are
described below.
I * Max
100mA
100 m~
71 m A
22 m A
14.1 m A
14.1 m A
14.1 m A
Unless the utmost in sensitivity or
a
standard
t e s t voltage is desired,
a
supply of about 100 V (e.g.,
a
90-V battery), with about 25 k a in series, is recom-
E Max
7 1 V
71
v
71 V
71 V
71 V
223 V
500 V
Range
Full Scale
1 R
I O ~
10Ofl
I k n
10 k n
100 k n
1 M R
Range
Multiplier
100 r n n
~n
1 0 0
100R
I kfl
10 k n
100 k n
REC 1 17 applies only up to
9999 R .
*
i t is preferable to limit current to avold shock
*
A t E X T GEN terminals.
hazard or to reduce voltage to 10 V.
**
Maximum allowance bridge voltage will not give maximum
test voltage.
1 H D L C
L-L
E I A STANDARD TEST VOLTAGES
(RS 196 FIXED-FILM RESISTORS
REC 11 7 LOW-POWER WI RE-WOUND RESISTORS)
*
at E X T GEN terminals
* *
cannot get required bridge voltage
* * *
limited to 71 V by bridge
Resistance
Range
less than 10
1 0 - 9 9 R
100
-
9 9 9 R
1000
-
9999R
10-99 kR
100 kfl up
1 H D L C
L-J
EIA STANDARD TEST VOLTAGES
(RS 172
-
F I X E D COMPOSITION ,RESISTORS)
BASIC MEASUREMENTS
2-4
E I A Max
Test Voltage
0.3 V
1 V
3
V
10
v
30 V
100 V
Bridge Mult
Range
1
a
1 0 0
100 R
I kR
10 kR
100 k R
Max Fridge
Voltage
+
* I
**
33 V
20
v
33 V
101 V
Resistance Range
2.7
-
9 9
n
100 - 9 9 9 R
1000
-
9 9 9 9 0
10 - 9 9 kR
100 k n up
voltage
E I A Test
R~~~~
0.5- I
v
0.5- 1 V
2.5- 3 V
8 - l O V
24 -3OV
80 -lOOV
Bridge Muit Range
i n
10 R
I 00
0
I
kR
I 0 kR
100 kR
Bridge*
Voltage
**
50
-
71 V***
27.5
-
33 V
16 -2OV
26.4
-
33 V
80
-
IOOV
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