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Helmut - Question on Crystal.asc
Dear Helmut,
I thiink you uploaded this file so I'm sending the question to you. In crystal.asc, located at <https://groups.yahoo.com/neo/groups/LTspice/files/%20Examples/Educational/Transient%20analysis%20of%20a%20crystal/crystal.asc> there is a statement under L1: IC=-100.8u I understand this is to establish an initial current. But how do we know which circuit it applies to, and how do we tell it is intended to set the current in L1? Does it also apply to L2? It seems to, but L2 has a DC offset so the initial swing is from zero to 150uA whereas L1 has no offset. There is no offset in the voltage sources V1 and V2, so it is not clear how the initial offset is established in L2. When you set an initial condition in this manner, how do you make a mental image of what is happening? For example, if I imagine a current is going through L1, I would think it has to charge C1. This would create an initial voltage across C1, but I have no way to tell how much that voltage will be. The same problem happens with L2 and C3. Do we consider the current is applied for zero time and terminates at the start of the transient analysis? BTW, I think you have provided an outstanding service to tens of thousands of engineers through your steadfast dedication to the LTspice group. I don't know how you manage to maintain your sanity over such a long time, but I offer my heartfelt gratitude for what you have accomplished. Thanks, Mike |
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Re: RE : Re: slow IGBT Simulation problem
I can see it, too, unfortunately. Vlad ______________________ -- holding, among others: a universal analog/digital filter, block-level models for power electronics (and not only), math blocks with a more stream-lined approach, some digital ADC, DAC, (synchronous-)counter, JKflop, etc. 2014-05-26 17:41 GMT+03:00 motauakil@... [LTspice] <LTspice@...>: > > ? > > Destinataire: motauakil@... > > Objet: [LTspice] Re: slow IGBT Simulation problem > > > Je vous rappelle que vous avez jusqu¡¯au vendredi 30 mai 2014 pour d¨¦poser au secr¨¦tariat enseignants votre fiche de v?ux pour la rentr¨¦e prochaine. KERVOILLARD Elise Secr¨¦tariat enseignants Lyc¨¦e Richelieu 64 rue George Sand 92501 RUEIL-MALMAISON T¨¦l : 01 58 83 20 17 Fax : 01 58 83 20 23 Courriel : > > |
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Re: RE : Re: slow IGBT Simulation problem
I got it also.?It (at least superficially) appears to be sent via the group:
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================================================================ Subject: RE : [LTspice] Re: slow IGBT Simulation problem Date: May 26, 2014 7:41:19 AM PDT Destinataire:?motauakil@... Objet: [LTspice] Re: slow IGBT Simulation problem Je vous rappelle que vous avez jusqu¡¯au vendredi 30 mai 2014 pour d¨¦poser au secr¨¦tariat enseignants votre fiche de v?ux pour la rentr¨¦e prochaine. KERVOILLARD Elise Secr¨¦tariat enseignants Lyc¨¦e Richelieu 64 rue George Sand 92501 RUEIL-MALMAISON T¨¦l : 01 58 83 20 17 Fax : 01 58 83 20 23 Courriel : Posted by:?motauakil@... Jim Wagner Oregon Research Electronics On May 26, 2014, at 12:05 PM, helmutsennewald@... [LTspice] wrote:
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Re: RE : Re: slow IGBT Simulation problem
John Woodgate
In message <psbkcu5qegym7hw3xd4yqhh2.1401115279761@...>,
dated Mon, 26 May 2014, "motauakil@... [LTspice]" <LTspice@...> writes: Who approved this rubbish? I hope the troll hasn't been admitted as a list member. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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Re: Ctrl_r to rotate an inductor
John Woodgate
In message <CAK-wn_4VATz=nfQ0uy+hDJTvqE2M2fqVdhLesuQoksSN_x9STA@...>, dated Mon, 26 May 2014, "Sam Jesse revrvr@... [LTspice]" <LTspice@...> writes:
The point which I was most concerned about is the fact that L3 is "rotated" unlike L1 and L2.The orientation in the schematic means nothing in real life. Only the 'polarity dots' have any significance, indicating the north (or south) poles of the magnet the inductor and its current produce. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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Re: Ctrl_r to rotate an inductor
Sam Jesse
Hi The point which I was most concerned about is the fact that L3 is "rotated" unlike L1 and L2.
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Re: Ctrl_r to rotate an inductor
John Woodgate
In message <CAK-wn_6=bn+xLOd_mBp9qofHnHq+39rP=WLhM8V0BH5DLuJ+XA@...>, dated Mon, 26 May 2014, "Sam Jesse revrvr@... [LTspice]" <LTspice@...> writes:
In the example of Files/Temp/ transformer.ascThat is a VERY big question, and nothing to do with simulation. The inductance values, with 1000:1 ratio, you show are hardly feasible for a practical transformer (except a toroid with a single-turn primary - that *might* work). K = 0.9 is difficult to achieve with a transformer having a magnetic core. 0.98 would be more practicable, and it hardly affects the simulation. Is the transformer supposed to work with the pulse input of 1.5 V and no load on the output other than the capacitor? The voltage applied and the current output determine the core size and winding area you need. It looks as though a ferrite toroid is your best choice but you need quite a big one to get 100 mH twice. I doubt you can get enough design guidance on the web; you really need a very good textbook. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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Ctrl_r to rotate an inductor
Sam Jesse
Hi What effect to inductor/transformer building does Ctrl_r mean in the physical sense?In the example of Files/Temp/ transformer.asc L1, L2 and L3. how can I build this home transformer project to "play" with?i.e. how to wind it to match the LTspice design? Thank you |
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slow IGBT Simulation problem
Hi Fellows, Hope all are doing well. ?I am trying to simulate basic igbt switching cercuit ( not yet with any specific model) so i found a basic circuit in file session of this group. It worked but its very slow after half of the pulse duration it seems as it stopped even after waiting ? it doesnot proceed much. My question is that how to make simulation faster in this case? does simulating igbt is time consuming as it appear? I am not very experienced with ltspice, please guide if i am wrong somewhere or i am doing any silly mistake in setting transient parameter.... For your reference link of files that i used from this group is given. |
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Re: LM2917 F/V Tachometer simulation problem
Hi I've been working on this since?the post your referring to went to the wrong group...:-/ Anyway... I was able to get?the macro model?working. I was about to ask someone if they could test the model when I noticed your post. Thanks for the follow-up. "The circuit, taken right out of Figure 14 in National Semi's Applications Note AN-162, is peculiar because the on-chip "ground" (VSS?) pin is not grounded. ?It is connected to a point that is nominally half-way between power and actual ground. ?That means some of the signal pins are well below on-chip VSS. ?Usually the on-chip VSS is the substrate, and nothing should ever be more negative than that. ?It just doesn't seem right." Yup, the schematic is a little unclear. There actually is a ground input on the schematic. Its Pin 12 shown in the BIAS section. All ground points on the schematic should be tied together and connected to?Pin 12. Pin?12 then should be grounded externally in the application circuit.? "In addition, there might be problems with the IC model too, in spite of the fact that it looks like a faithful replica of their Figure 2. ?The on-chip regulator is a few volts off. ?The input pin has a 10K series resistor, which seems to prevent the input from noticing zero-crossings (i.e., it's impossible to bring pin 1 low enough to ever toggle the Schmitt trigger ... so it never sees any AC input!). ?There may be issues with mismatch between diodes and transistors, which prevents some transistors from ever turning on. ?Those are the problems I saw so far I can see nothing happening in the Charge Pump. ?Its input seems to be forever stuck high. ?The problem starts in the input hysteresis amplifier" In the description of the Hysteresis Amplifier, I noticed this statement: "D4 and Q7 are identical geometry devices, so What I did here is replace all diodes in the schematic, except the zener of course, with transistors. Once I did that, everything started working...:-). The?circuit output values all seem to match values expected using the equations on the data sheet. "I have a strong suspicion that Figure 14 might not actually work" I haven't tried this yet with the new changes but I will. Can someone check the new LM2917 component? eT |
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Re: Fluorescent lamp model F40WW
John Woodgate
In message <llt5bp+foraj9@...>, dated Sun, 25 May 2014, "helmutsennewald@... [LTspice]" <LTspice@...> writes:
I wonder which schematic you use.That's a 'flourescent' lamp -you can see the flour on the inside of the tube! (;-) -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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Re: plotting the difference of voltages
John Woodgate
In message <llsfp5+1ji152k@...>, dated Sun, 25 May 2014, "helmutsennewald@... [LTspice]" <LTspice@...> writes:
A transformer can only transport AC voltage and current.This is, of course, true if you wait long enough, but it can be surprising how long a transformer passes an unsymmetrical signal. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |