Best regards,

Helmut

Dear Mr Andy,

Thanks for your suggestion. I chose one potentiometer from the all_files folder. But still I am unable to simulate my circuit if I use this component in my circuit. Same error message appears again - "Unknown sub-circuit called in: x001 n003 n008 nc_01 potentiometer rtot=50K wiper = 5"

Do it change anything after placing ths component in my circuit?

Thanks & Regards,

M.Rakesh sharma.

Some one or two months ago mention was made of a book “The LTSPICE IV Simulator” written by Gilles Brocard, published by Wurth Electronik, ISBN 978-3-89929-258-9.

I have used LTSPICE for about three years and probably simulated over 100 circuits for both my own and work purposes, but like many others I struggle to interpret the sparse help files and I knew that I had much to learn to improve my knowledge of the simulator. ?I decided to purchase a copy of the book even though it was $60 US here in Australia. I rationalised that since the simulator was free, this cost was reasonable if the book turned out to be of value.

Until now I have been slowly improving my skills by keeping a notebook of tips gleaned mainly from this forum. I have also read several of the tutorials produced by universities and others to introduce LTSPICE to undergraduates. These all help but because the information is somewhat random in its coverage and no doubt because I have not taken the time to organise it properly, it can sometimes be of limited help. I also refer to examples in the files section and information gleaned from other web sites. No doubt this would be sufficient if I had the time to spend learning the simulator, however like many others I am time poor at present.

The purpose of this post is to provide some feedback on the book. I am only about one third through it but I am able to report that I consider it as having been a good purchase. Sure the style of writing is very dry and some of the phrasing has that awkward feel that often occurs when technical books get translated to English, but the coverage of the subject appears to be thorough. Even though I would have liked a more comprehensive index, so far I have been able to locate all the information I have looked for.

I thought this feedback may be of interest to others in a similar situation to myself. I have no association with the author or publisher.

Finally, since I rarely post, let me take the time to say thanks for the effort made by Helmut and others who step in to answer questions and offer advice. It is appreciated, if rarely acknowledged, by the many followers of the site.

I have uploaded to the Temp folder an example circuit from where I have included the .meas commands for the phase and gain margins. For further explanations, please see Measure_Margins.asc. I have also reduced the step size of the .ac simulation in order to get more precise results.

The second condition in the Omicron article means that the voltage loop gain is only a good approximation for the loop gain as long as the loop gain is much larger than the ratio |Zout/Zin|. Because the first condition means that this ratio has to be much smaller than 1, this second condition is automatically satisfied at |T|=1 (or 0 dB), where you measure the phase margin.

Best regards,

Frank

---In LTspice@..., <405a82e5@...> wrote:

Mike,

If you only want to put one cursor on the trace up can click right or left click on the label. It works fine for me, if I set the cursor near the 0 dB point before I expand the trace. It takes only a few seconds to do it. For example it is easy to get -934.5 udB and 107.19 degrees at 9.166 MHz

Rick

I have uploaded to the Temp folder an example circuit from where I have included the .meas commands for the phase and gain margins. For further explanations, please see Measure_Margins.asc. I have also reduced the step size of the .ac simulation in order to get more precise results.

The second condition in the Omicron article means that the voltage loop gain is only a good approximation for the loop gain as long as the loop gain is much larger than the ratio |Zout/Zin|. Because the first condition means that this ratio has to be much smaller than 1, this second condition is automatically satisfied at |T|=1 (or 0 dB), where you measure the phase margin.

Best regards,

Frank

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When some sort of modulation is going on, energy gets transferred from the signal at the peak, into the sidebands around it. ?So as the amount of modulation gets worse, I think I would expect to see the peak shown by the FFT to decrease, while the width increases.

-- 

AC2CL 

I do not think there is any thrill that 
can go through the human heart like that felt by the inventor as 
he sees some creation of the brain unfolding to success... 
Such emotions make a man forget food, sleep, friends, love, everything. 

- Nikola Tesla 

 

---In ltspice@..., <405a82e5@...> wrote:

Thanks, Frank.

The omicron article gives good information, including derivations. Thanks for posting the link.

The first condition is pretty easy - inject the signal at the input to the op amp as shown in Lokere's demo.

I don't understand the second condition. I think it applies when you are injecting a signal across a small resistor via a transformer, where the impedances are part of the result. I don't think it was ever mentioned for applications in SPICE.

Would you care to help translate your .measure commands to the Voltage Injection method? You are familiar with the method and could avoid a lot of errors that others may encounter.

Thanks,

Mike

?

?

I have uploaded to the Temp folder an example circuit from ?where I have included the .meas commands for the phase and gain margins. For further explanations, please see Measure_Margins.asc. I have also?reduced the step size of the .ac simulation in order to get more precise results.

?

The second condition in the Omicron article means that the voltage loop gain is only a good approximation for the loop gain as long as the loop gain is much larger than the ratio |Zout/Zin|. Because the first condition means that this ratio has to be much smaller than 1, this second condition is automatically satisfied at |T|=1 (or 0 dB), where you measure the phase margin.

?

Best regards,

?

Frank???????????????????????????