Date: Wed, 10 Aug 2011 11:08:41
Author: --- "Brian Holton"
Subject: Re: Extech DMM Question
Post:
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I
V meter
V total
R
R meter
=09
10.0
0.043
0.99
98.9
4.3
=09
19.6
0.085
1.94
99.0
4.3
=09
29.2
0.128
2.80
95.9
4.4
=09
40.9
0.182
4.00
97.8
4.4
=09
49.8
0.224
4.80
96.4
4.5
=09
60.0
0.275
5.80
96.7
4.6
=09
70.0
0.329
6.80
97.1
4.7
=09
80.7
0.390
7.90
97.9
4.8
=09
90.0
0.450
8.80
97.8
5.0
=09
100.8
0.525
9.90
98.2
5.2
=09
110.9
0.607
10.80
97.4
5.5
=09
120.4
0.720
11.80
98.0
6.0
=09
130.3
0.809
12.80
98.2
6.2
=09
140.0
0.970
13.70
97.9
6.9
=09
151.5
1.187
14.80
97.7
7.8
=09
160.0
1.557
15.60
97.5
9.7
=09
170.0
1.978
16.60
97.6
11.6
=09
180.6
2.300
17.70
98.0
12.7
=09
=20
=20
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On =
Behalf Of George M. Caplan
Sent: Wednesday, August 10, 2011 10:10 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Extech DMM Question
=20
Thanks for the comments so far.
I am *not* using this meter to measure the waveforms of the stepper =
motor.
Sorry, I didn't make that clear.
I *am* using it to measure DC milliamps in a simple circuit with some =
#48 bulbs.
I expected a constant resistance.
If I have time, I will do more measurements today. In any case, my =
readings seem to correspond to those of Brian H. (although I did not get =
the attachment).
The Fluke "burden voltage" corresponds to a fixed resistance for a given =
scale, which is what I'd expect. 11 mV/mA is 11 ohms, which is =
(obviously) constant, but it's higher than I would have guessed. Anyway, =
for the Extech I expected a constant value for a particular range =
setting. Since the value is not constant, the meter can clearly affect =
the circuit more than I realized .. and in a somewhat unpredictable way.
I apologize for this email rambling. I am trying to do three projects at =
once, so I can't focus all my thought on one. I am sure none of you have =
ever had that problem.
=20
George
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IV meterV totalRR meter10.00.0430.9998.94.319.60.0851.9499.04.329.20.1282.8095.94.440.90.1824.0097.84.449.80.2244.8096.44.560.00.2755.8096.74.670.00.3296.8097.14.780.70.3907.9097.94.890.00.4508.8097.85.0100.80.5259.9098.25.2110.90.60710.8097.45.5120.40.72011.8098.06.0130.30.80912.8098.26.2140.00.97013.7097.96.9151.51.18714.8097.77.8160.01.55715.6097.59.7170.01.97816.6097.611.6180.62.30017.7098.012.7 From:=
=
tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On =
Behalf Of George M. CaplanSent: Wednesday, August 10, =
2011 10:10 AMTo: tap-l@lists.ncsu.eduSubject: Re: =
[tap-l] Extech DMM Question T=
hanks for the comments so far.I=
am *not* using this meter to measure the waveforms of the stepper =
motor.S=
orry, I didn't make that clear.I=
*am* using it to measure DC milliamps in a simple circuit with some #48 =
bulbs.I=
expected a constant resistance.I=
f I have time, I will do more measurements today. In any case, my =
readings seem to correspond to those of Brian H. (although I did not get =
the attachment).T=
he Fluke "burden voltage" corresponds to a fixed resistance =
for a given scale, which is what I'd expect. 11 mV/mA is 11 ohms, which =
is (obviously) constant, but it's higher than I would have guessed. =
Anyway, for the Extech I expected a constant value for a particular =
range setting. Since the value is not constant, the meter can clearly =
affect the circuit more than I realized .. and in a somewhat =
unpredictable way.I=
apologize for this email rambling. I am trying to do three projects at =
once, so I can't focus all my thought on one. I am sure none of you have =
ever had that problem. G=
eorge
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