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Old 19th October 2014, 08:42 PM   #1
Elvee is offline Elvee  Belgium
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Default What's LTspice doing there?

I reran an old circuit of mine, and, the spice log reported two sets of values, with one in parenthesis. What does it mean? I had never seen that when I had launched this circuit previously.
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Old 20th October 2014, 06:47 PM   #2
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You have two Fourier commands active on your schematic; 1kHz and 100kHz. Your sine source is set to100kHz.
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Old 20th October 2014, 06:51 PM   #3
Mooly is offline Mooly  United Kingdom
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I was just going to ask the same question. I'm seeing this on all my sims.
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Old 20th October 2014, 11:21 PM   #4
fas42 is offline fas42  Australia
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You could always ask the man, Mike, directly: <LTspice@linear.com>. I've done that, and got an excellent response, that was very helpful ...
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Old 20th October 2014, 11:43 PM   #5
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I've just updated and I'm seeing this also.
Code:
Circuit: * Z:\home\tarkus\LTspice files\my files\tube\6CX7-pre\6cx7-pre.asc

Direct Newton iteration for .op point succeeded.
N-Period=1
Fourier components of V(out)
DC component:-0.00200956

Harmonic    Frequency     Fourier     Normalized     Phase      Normalized
 Number       [Hz]       Component     Component    [degree]    Phase [deg]
    1       1.000e+03    2.827e+00    1.000e+00      179.94°        0.00°
    2       2.000e+03    4.569e-03    1.616e-03       89.62°      -90.33°
    3       3.000e+03    2.659e-05    9.403e-06       -1.13°     -181.08°
    4       4.000e+03    7.972e-07    2.820e-07     -150.40°     -330.35°
    5       5.000e+03    5.517e-07    1.951e-07      179.99°        0.04°
    6       6.000e+03    4.565e-07    1.615e-07      179.99°        0.05°
    7       7.000e+03    3.915e-07    1.385e-07      180.00°        0.05°
    8       8.000e+03    3.427e-07    1.212e-07      180.00°        0.05°
    9       9.000e+03    3.048e-07    1.078e-07      180.00°        0.05°
Total Harmonic Distortion: 0.161606%(0.161605%)



Date: Mon Oct 20 18:39:45 2014
Total elapsed time: 2.411 seconds.

tnom = 27
temp = 27
method = modified trap
totiter = 196676
traniter = 196666
tranpoints = 98334
accept = 98332
rejected = 2
matrix size = 14
fillins = 0
solver = Normal
Matrix Compiler1: 840 bytes object code size  1.5/1.4/[1.2]
Matrix Compiler2: 1.10 KB object code size  1.3/1.4/[1.2]
Hmm.
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Old 21st October 2014, 11:38 AM   #6
Mooly is offline Mooly  United Kingdom
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Where is the 10th harmonic ?
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Old 21st October 2014, 05:19 PM   #7
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Seems like it's defaulting to the 9th ".four 1k V(out)". When I specify ".four 1k 10 10 V(out)", it goes out to the 10th.
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Old 22nd October 2014, 07:38 PM   #8
Mooly is offline Mooly  United Kingdom
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Mike Engelhardt very kindly replied to me asking what was going on and the answer is...

The 2nd figure an alternative method of computing THD. It nominally includes
all harmonics but numerically difficulting in identifying the fundelmental
limits it actually use. It's just bonus information for the guy that asked for
the feature. You can ignore it. But is the number is higher the previous
number, it is an indication that you didn't include enough harmonics in
your THD calculation.
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Old 23rd October 2014, 03:44 PM   #9
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by Mooly View Post
Mike Engelhardt very kindly replied to me asking what was going on and the answer is...

The 2nd figure an alternative method of computing THD. It nominally includes
all harmonics but numerically difficulting in identifying the fundelmental
limits it actually use. It's just bonus information for the guy that asked for
the feature. You can ignore it. But is the number is higher the previous
number, it is an indication that you didn't include enough harmonics in
your THD calculation.
Quite strange: in the example I gave, the second figure is actually lower than the first (zero in fact)
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Old 23rd October 2014, 06:36 PM   #10
Mooly is offline Mooly  United Kingdom
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Dunno on that Elvee. You are way ahead of me with LT
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