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PTC model with internal temperature rise 18
I have uploaded 2 files to the temp section that model a 120 degree PTC thermistor, (the Epcos B59008C0120A040 from: http://www.epcos.com/inf/55/db/ptc_03/01770179.pdf ) including the nonlinear behavior, modeled as 4 different temperature coefficient resistors in series parallel. The model is in file PTC1.asc and the symbol is PTC_resistor.asy The model also includes the internal temperature rise and thermal time constant (which I guessed at, for lack of hard data). The symbol I created for it has a third node that produces a voltage that represents the internal temperature, with 1 volt = 1 degree C. The curve across the resistor symbol indicates the 4 slopes in the model. Everything I see this model doing looks pretty reasonable, but I would appreciate anyone going over the whole thing and making suggestions for improving it. This was my first foray into model building with Spice.
Started by jpopelish @ · Most recent @
Simulation runs very slowly: test.asc 97
Hi All, In the uploaded file test.asc, I¡¯m having a problem with a simulation getting stuck. Would appreciate a look. Thanks, Chris
Started by Christopher Paul @ · Most recent @
Simulation on LTspice about of Power Quality and Energy Efficient 2
Hello , My name is Mario Martinez , i want to know about sumulation circuits of squematics what represented for analisys of energy quality and energy efficient , i am ecuatorian
Started by mmartine @ · Most recent @
.MEAS scripting 21
I have a fairly large model that I need to probe many of its components for Voltage, Current, and/or Power over a run period. Not difficult once I get the syntax correct, for individual parts withy clear net names, but it gets hairy, or at least tedious, to build up the .meas statements for many parts. In the plot pane, in Add Traces, I see a syntax like ¡°Id(M1), Ie(Q1), I(u1:E1), etc.¡± Is there a form of that for Voltages, referring to other component pin numbers, ¡°V(R1:1)¡± or the like? Dave
Started by Bell, Dave @ · Most recent @
Switching Speed of a BJT 6
On 03/04/2025 09:26, jacfev via groups.io wrote: This is not such a simple question. What are your parameters for switching speed? Presumably rise and fall times? How about delays times? You can still have fast rise and fall times, but with a significant delay time if the transistor is driven into saturation. I would say that Bf is not one of the most influential parameters for speed. More important are the internal capacitances: Cje and Cjc, and transit times: Tf and Tr. Tr sets the reverse recovery time, i.e. charge storage in the base region on switch off - this is critical in saturated BJT switching circuits. To assess the speed, you need to .MEAS the rise and fall times at the output, and the turn-on and turn-off delay times referenced to the input source waveform. -- Regards, Tony
Started by Tony Casey @ · Most recent @
20nm PTM file not working in LTspice 34
I am trying to build 6T SRAM using 20nm but when i run the simulation i am having the errors saying parameter level = 72 and also other bunch of errors. my 180nm file ran properly but when i tried for 20nm it's not working although i changed W/L ratio from L=0.18 ,W= 0.64 to L= 0.02 to W= 0.3. What should i do ?
Started by Say Die. @ · Most recent @
CD4000 test 17
I am trying to work with the CD4000_v.lib and am getting errors when trying to run. Would someone provide me some guidance as to what is set up in error? File uploaded to temp: CD_test.zip This is using the CD4013 as a counter. I have included the latest CD4000_v.lib and the CD4013B symbol from the files section to make it easy.
Started by DerekK @ · Most recent @
creating PNP caracteristicsby sweeping plot in LTspice from a circuit I built 10
Hello , in the attacehd zipped file I have created a basic PNP biasing circuit . The simultion is in time domain , I added plots of different ports. Is a there a way by clever type of sweep to recreate the basic characteristics plot of the attached PNP plot? Current vs Vce plot. Thanks. /g/LTspice/files/Temp/03_01_25.zip
Started by john23 @ · Most recent @
Conductance Negative 17
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
Started by sebastian.herrera@... @ · Most recent @
Good settings for RIAA square wave 17
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
Started by Carlos E. Mart¨ªnez @ · Most recent @
Beginner's Question re LT Spice and RF Filter Design 7
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."
Started by k6whp @ · Most recent @
Simulating Using PyLTSpice Takes Too Long 26
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")
Started by davitkharshiladze26@... @ · Most recent @
.MEAS syntax with variable parameters 7
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
Started by Bell, Dave @ · Most recent @
Inductance modeling using table issue. 6
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 ?
Started by Tintari Dumitru @ · Most recent @
FFT spectrum calculation algorithm ? 8
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.
Started by ericsson.sunshine@... @ · Most recent @
Model of BF970 ? 3
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.
Started by Kerim @ · Most recent @
Singular matrix 16
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.
Started by pilou@... @ · Most recent @
Sawtooth waveform by simple BJTs, but dips at the top. 17
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.
Started by ericsson.sunshine@... @ · Most recent @
Sallen Key Filter Capacitor at feedback network 4
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.
Started by antonios.doukakis@... @ · Most recent @
LTspice non-inverting Opamp loop gain. 9
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
Started by Bell, Dave @ · Most recent @
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