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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
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Old 6th February 2018, 11:22 AM   #1031
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
One other way is to scroll the circuit you have and make it small, then use the copy function to draw around and then drag the copy alongside.

Now delete any duplicate .op commands etc and alter as necessary any duplications in shared rails/outputs and so on.

You can then run the two circuits together and alter one while keeping the other the same.

(one odd thing with this example that I can't fathom. If I keep the two input voltages separate then the second circuit has a gain 6db higher than the first on an 'AC Analysis' run, however a 'Transient' run shows the same output voltage. Why is that ?)
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Old 6th February 2018, 11:32 AM   #1032
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
First picture was wrong one above. Should be this:
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Old 6th February 2018, 02:47 PM   #1033
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by Mooly View Post
First picture was wrong one above. Should be this:
I have been playing with that but you must make sure that the sources and node names have different names (they will not when copied) or feed both circuits from the same source.

Jan
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Old 6th February 2018, 07:12 PM   #1034
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
Thanks Jan... I'm puzzled as I'm sure I got that right.

I didn't save the sim, but I do have another 'dual' sim set up for Doug Selfs old precision preamp and I see exactly the same issue there. In fact the 6db difference is present on the input voltage source itself.

Nutz... lets try a voltage source on its own repeated three times. Hmm, so this also gives a 6db 'increase' for the first copy and another increase of around 3.5db for the third copy.

I must be overlooking something really obvious but I can't fathom it.
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Old 6th February 2018, 07:55 PM   #1035
Hans Polak is offline Hans Polak  Netherlands
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Quote:
Originally Posted by Mooly View Post
Thanks Jan... I'm puzzled as I'm sure I got that right.

I didn't save the sim, but I do have another 'dual' sim set up for Doug Selfs old precision preamp and I see exactly the same issue there. In fact the 6db difference is present on the input voltage source itself.

Nutz... lets try a voltage source on its own repeated three times. Hmm, so this also gives a 6db 'increase' for the first copy and another increase of around 3.5db for the third copy.

I must be overlooking something really obvious but I can't fathom it.
What's your problem.
V1 is 1 Volt, V2 is 2 Volt and V3 is 3 Volt, resp 0dB, 6dB and 9.54dB.
Everything is O.K.
Also in your dual Amp diagram one source is 1 Volt and the other 2 Volts, so output is 6dB higher for the second Amp.
Hans
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Old 7th February 2018, 07:28 AM   #1036
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
Thanks Hans, a true mental block on my part

I was thinking when I duplicated the circuit I would have to change the 'voltage reference' designators manually to avoid duplication and for some reason I kept going to the 'AC Amplitude' box on the voltage sources thinking it was that.

Duh
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Old 7th February 2018, 11:45 AM   #1037
kees52 is offline kees52  Netherlands
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Hi all

The 64bit version of ltspice is corrected, there are no crashes anymore, the writer has update that after mine mail about it and where to find the problem.

Now it works fine.

regards
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Old 7th February 2018, 12:35 PM   #1038
davidsrsb is offline davidsrsb  Malaysia
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The new version is much better than the old 4 these days
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Old 7th February 2018, 01:29 PM   #1039
Mooly is offline Mooly  United Kingdom
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Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
That's good to know Thanks for the update.
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Old 10th February 2018, 09:23 PM   #1040
woofertester is offline woofertester  United States
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I am a noob to LTSPICE. Here is a circuit that was posted in Pass Labs. It gives an error that the includes are missing.

Where are workable models for the transistors and how can I make this portable so that anyone can run it?
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