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Dear all, I am trying to simulate a circuit with negative conductance using transistors and passive components. Does anyone have a circuit for this? Best regards. Sebastian

Hi, This should be the first time I will be using a SW to test a RIAA preamp response. I was thinking of copying the settings I use for testing power amps, but I am not sure it's correct. They are: PULSE(-.4 .4 0 10n 10n 25u 50u 10) Would they be fine for this new test? Thanks! Carlos

Am designing a low pass filter for the 20m amateur band, code below. (My apologies if this violates group protocol. Advise and I will adhere in the future.) I note that the display shows this model to initially be -6dB and wonder why. Again, truly a beginner. Links to appropriate material gratefully received. Thank you in advance. -- William, k6whp -------------------- "Cheer up, things could get worse. So I cheered up and things got worse."

Hello Everyone, I am trying to simulate very simple circuit using PyLTSpice. However, simulation takes too much time. It takes 1 second for the simulation to complete. Even when I increased the complexity of the circuit, time taken for simulation still stays approximately the same. I increased-decreased number of freuqncy points in my ac analysis, this had little to no effect on simulation runtime. I feel like most of the simulation time is spent reading-writing files. Does anybody has any suggestions that can be beneficial to speeding up the process? Currently, I am using LTSpice simulator, as seen on the third line. import time from PyLTSpice import SimRunner from spicelib.simulators.ltspice_simulator import LTspice # Create the netlist file (simple_lc.cir) netlist_content = """* Simple LC Resonant Circuit V1 N001 0 AC 1 L1 N001 N002 10uH C1 N002 0 1pF R1 N002 0 50 .ac lin 1500 40Meg 60g .save V(N002) .end """ # Save netlist netlist_filename = "simple_lc.cir" with open(netlist_filename, "w") as f: f.write(netlist_content) LTC = SimRunner(output_folder='/temp', simulator=LTspice) # init simulation runner for i in range(1,10): # iterate ove reverything t1 = time.time() LTC.run(netlist=netlist_filename) LTC.wait_completion() print(f"{t1 - time.time()} - Simrun")

I’m frustrated by failure of a time measurement I’m trying to make. My circuit generates a pulse train with parameterized width, Pw. I want to measure a delay, from a rising edge of one node, N0, to the next rising edge of another node, Nx. Due to a filter action, the amplitude of V(nx) is dependent upon a resistor whose value is stepped, from run to run. Because of that, I want to make the trigger (target) amplitude a variable, say 90% of the MAX() amplitude of node Nx. .meas VNx MAX V(Nx) FROM {5*Pw} TO {25*Pw} .meas T1 TRIG V(N0)=2.25 TD=3u RISE=1 TARG V(Nx)=250m TD=3u RISE=1 Measurement 1 correctly returns a peak value from say 0.5V to 4.5V. Measurement 2 returns a time that’s too close to the stat of Rise, instead of near the peak level. T1 Fails if I use this instead: .meas T1 TRIG V(N0)=2.25 TD=3u RISE=1 TARG V(Nx)={0.9*VNx} TD=3u RISE=1 Help?? Dave

Hi! I try to model an inductor using table. When i simulate this inductor, inductance value initially is changed according to the table that i include, but close to end off table inductance value didn't respect value from table. I try to change simulation time, and this make a negative effect on inductance (i don't know why!). Can someone help me with this? blob:/29cb438c-88fc-4eab-81d2-06d860dc8640 this is how inductance need to be changed with bias current. blob:/906f8161-46e1-4558-a50a-630d24f881b5 -- Circuit blob:/c5224e18-4379-40dd-b2de-90c8572811c4 -- Simulation result Text in InductorTable.txt: B1 tb 0 V = Table(I(V2), -70, 30u, -50.24, 30u, -49.75, 32u, -48.48, 37u, -46.35, 42u, -43.83, 45u, -41.60, 50u, -39.46, 57u, -37.51, 63u, -35.57, 69u, -33.52, 79u, -31.57, 86u, -29.52, 96u, -27.67, 107u, -26.10, 119u, -24.54, 127u, -23.26, 138u, -21.79, 149u, -20.13, 162u, -18.95, 173u, -17.67, 184u, -16.69, 195u, -15.50, 208u, -14.13, 222u, -12.94, 237u, -11.76, 250u, -10.67, 263u, -9.39, 276u, -8.20, 292u, -7.02, 305u, -6.13, 318u, -5.04, 330u, -3.86, 344u, -2.88, 351u, -1.80, 357u, -0.83, 362u, 0, 364u, 0.83, 362u, 1.80, 357u, 2.88, 351u, 3.86, 344u, 5.04, 330u, 6.13, 318u, 7.02, 305u, 8.20, 292u, 9.39, 276u, 10.67, 263u, 11.76, 250u, 12.94, 237u, 14.13, 222u, 15.50, 208u, 16.69, 195u, 17.67, 184u, 18.95, 173u, 20.13, 162u, 21.79, 149u, 23.26, 138u, 24.54, 127u, 26.10, 119u, 27.67, 107u, 29.52, 96u, 31.57, 86u, 33.52, 79u, 35.57, 69u, 37.51, 63u, 39.46, 57u, 41.60, 50u, 43.83, 45u, 46.35, 42u, 48.48, 37u, 49.75, 32u, 50.24, 30u, 70, 30u) My question is: Why inductance value didn't respect the table ? Thanks for your help ?

Hi, : May I ask about FFT feature ? If in a waveform viewer, I want to do FFT analysis of a chosen node, which may has multiple frequency components varying during whole simulation time interval. Can it be done to separate the whole simulation time into several intervals by eg: zoom-in feature, then run the FFT feature only for the "zoom-in"ed waveform data, to see what's the freq component in these data ? I say so, because, some applications , eg: OFDM modulation, may have the multiple freq components in modulated signal, and may vary the amplitude depending on transmitted data in different time interval. It helps to analyze if FFT could do analyzing of separated time interval in a single waveform. Is this feature supported ? Thank you very much. Best regards.

BF970 is an PNP transistor for UHF band (fT=1000 MHz) from Vishay. I visited Vishay site but there was no sign of BF970 (very old). I hope its spice model exists somewhere or of equivalent UHF PNP transistor. Thank you.

Hello everybody, I'm working on a schematic and encounter a "singular matrix" error. I know there are as many cause than people in the mankind, but I would like to have advices to avoid this sort of things. I'm aware that there are a lot of maths in the background too :'( Thanks a lot in advance for your help.

Hi, : I have uploaded the file named '20250318_bootstrap time-based triangle-wave generator for frequency sweep.asc' at temp. /g/LTspice/files/Temp/20250318_bootstrap%20time-based%20triangle-wave%20generator%20for%20frequency%20sweep.asc The idea is to generate a sawtooth waveform for jittering in PWM. But at the top peak, Vout dips, it shows flaw of discontinuity. The image showing the phenomenon. /g/LTspice/photo/301350/3897404?p=Created%2C%2C%2C20%2C2%2C0%2C0 If you could share some opinions to fix it, I much appreciate you very well. Wish you all happy & healthy. Best regards.

Hello everyone, I am designing an Analog Front-End for biosignals (EMGs). You can find the corresponding circuit here /g/LTspice/files/EMG_AFE.asc. I have selected INA317 as an instrumentation amplifier and I am trying to design a 2nd order low pass filter after the InAmp stage. The problem is at Capacitor C3. If I remove the capacitor and connect the path to ground, the circuit behavior is not as expected. However the classic Sallen Key circuit topology does not contain this capacitor. Should someone has any idea why is it necessary in this particular configuration with the INA317, I would be very grateful. Thank you in advance.

You will soon be told this forum is for LTspice-specific questions, not for electronic design. :{) But I would suggest: https://www.analog.com/en/resources/glossary/non-inverting-op-amp.html Dave

I want make multiple runs of a model which will output a waveform to a .wav file. Each run will step a parameter, all of which works as intended, except, I need to change the filename each time. This illustrates the intent, but not surprisingly, errors off on the last line: .step param stp 1 6 1 .param Vcon table({stp}, 1,-2, 2, -1, 3, 0, 4, 1, 5, 2, 6,3) .wave {Stp}.wav 16 44.1k V(Out) Any suggested better syntax? I’ve tried several… Thanks! Dave

LTspice 24.1.5 I thought AKO could be used with NJF. Content of BJT_mod.txt: ........... .model NJ AKO:NJ20 NJF() .model NJ20 NJF ( VTO=-2.5 BETA=1m LAMBDA=0.01 RD=100 RS=50 + CGD=2p CGS=5p IS=1e-14 PB=0.7 FC=0.5 ) .......... Error produced in log: BJT_mod.txt(43): Syntax error: Unexpected input. .model NJ AKO:NJ20 NJF() ^^ I guess not? I tried removing NJF() from AKO statement but it didn't help.

I just wandered into files/Temp to see what was new but can only sort by "Type" or by "Name". I'd bookmarked /g/LTspice/files/Temp?p=updated,,,20,2,0,0 so I can get them in new-to-old order, but (being lazy) I usually just got to Temp and choose sort by date. Is this intentional or should I make my bookmark much easier to hit? Many thanks, Donald.

Hello, in some models I found some double "*": what's the meaning of this operator ? Thanks a lot in advance.

Hello everyone, I am trying to simulate Four switch non inverting buck boost converter with two different genesic switches G3R60MT07J and G3R75MT12J. The library files are encrypted, so I cannot make any changes there. I have tried various methods like increasing time step and tolerances, skipping initial operating point solution etc. but nothing is working for me. Any suggestions regarding how to resolve this issue?

it's a lot of time that a looking for a a model ltspice lm317 and lm337 made by the same hand. Someone could kyndly tell me where I can find them? Many thanks Andrea

Hello, Recently I compiled several models created by another group's member into one single library. Moreover, I slightly modified them for my need but I think it could be useful for other people here. I tried to contact the original author on his own email to ask his authorization, but I didn't have his reply yet. Moreover, it seems that he didn't come on the group since a long time. His there a rules on the forum for this kind of situation, or am I free to publish here without his authorization (but by mentioning his name however...) ? Thanks a lot in advance for your advices, Pascal

Sorry for FAQ. How can I renumber the parts number? I heard "shift+ctrl+alt+R" is available. But no change appear. Hidehiko JA9MAT.