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6 votes
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The output of my rectifier which should be charging a capacitor on LTSpice is extremely jumpy and inconsistent

You are not measuring the voltage across the capacitor as the ground is on the wrong node. The output node may be floating (depends on the model associated with "D") which will cause ...
qrk's user avatar
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5 votes
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Unable to get my astable multi-vibrator working in LTspice

Here is one problem: The output of the op-amp is connected to GND. There may be other problems.
Fabio Barone's user avatar
  • 1,522
5 votes

TL494 step-down converter unable to run LTSpice

You have floating nodes (that are not connected to anything) connect all nodes. For nodes that are not connected use a 1e9Ω resistor or other large value to simulate air. Edit: For convergence ...
Voltage Spike's user avatar
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5 votes

The output of my rectifier which should be charging a capacitor on LTSpice is extremely jumpy and inconsistent

You should measure the voltage across the capacitor rather than the capacitor relative to one side of the AC input. Also, it's bad practice to use automatically named nodes- always name them yourself. ...
Spehro Pefhany's user avatar
5 votes
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UCC25800 PSpice model

Look at the very top line: - ...
Andy aka's user avatar
  • 443k
4 votes

UCC25800 PSpice model

From a comment: Is it possible to decrypt the .lib file for use in LTspice? Since the Pspice model in the question is from TI, performed a search on the TI forum which gave: Decrypt PSPICE MODEL of ...
Chester Gillon's user avatar
3 votes
Accepted

How to create a PWM source with fixed frequency and decreasing duty cycle (at some interval) in LTspice?

Probably brute-forcing a solution using a PWL source is the quickest way to a solution. It's very useful for weird and/or complex sources. Once you dabble in generating your own PWLs using a ...
Ste Kulov's user avatar
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3 votes

How to create a PWM source with fixed frequency and decreasing duty cycle (at some interval) in LTspice?

For an arbitrary stimulus in SPICE I write a program in some other language (I like AWK, you might prefer something else like Python) that writes an output file containing the definition of a PWL ...
John Doty's user avatar
  • 2,525
3 votes
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TL494 step-down converter unable to run LTSpice

I suggest replacing the MOSFET with an ideal switch (voltage-controlled switch). This simplifies the simulation and avoids the need for an accurate MOSFET model. This also allows you to remove the ...
Fabio Barone's user avatar
  • 1,522
3 votes

How to measure flux in transformer in LTspice?

None of them is correct. flux1 looks more reasonable because flux2 uses unswitched windings as well. Remember the transformer ...
Rohat Kılıç's user avatar
3 votes
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TL494 step-down converter high voltage LTSpice

You are using an N channel MOSFET and that requires a driver that is boot-strapped: - Unfortunately, you don't appear to have implemented boot-strapping correctly. For instance, consider this circuit ...
Andy aka's user avatar
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2 votes
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How can I run a noise simulation in LTspice for a differential input circuit?

I've reviewed a few related questions about multiple sources for noise analysis and tried to reproduce the posters' underlying problem. What if this problem results from them misunderstanding the ...
V.V.T's user avatar
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2 votes

Understanding optocoupler's operation through simulation

Let's run a sim... CTR looks very different from the datasheet (non saturated case): Here's the model from LTSpice ...
bobflux's user avatar
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2 votes

Understanding optocoupler's operation through simulation

The datasheet simply says CTR is 20% minimum and 50% typical. And that is at If=10mA. Datasheet does not say what is the maximum CTR. So if simulator result shows 70% CTR, it is within specification, ...
Justme's user avatar
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2 votes

How can I take parameters from power NMOS and power PMOS transistors and translate these into LTspice simulations?

You need to do it this way: ...
G36's user avatar
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2 votes

Several base current values on the same graph

You can .dc a current source into the base and plot the collector current:
tobalt's user avatar
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2 votes

Several base current values on the same graph

In CircuitLab you can Run a DC Sweep with a Second Parameter simulate this circuit – Schematic created using CircuitLab You can click on the simulate this circuit link above to enter the ...
Math Keeps Me Busy's user avatar
2 votes

Several base current values on the same graph

If you would like to have in your diagram equally spaced base currents I recommend to use not a voltage source with a resistor at the base but instead a current source which can be stepped through ...
LvW's user avatar
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2 votes

Several base current values on the same graph

Use the "STEP PARAM" command: .step param RX list A B C D E F G If you change R6's resistance value (1000) to something like ...
Rohat Kılıç's user avatar
2 votes

Vpeak to peak using LTspice

Are you trying to put one voltage on the horizontal axis and another on the vertical axis, like this? If so, all you need to do is right-click on what is normally the time axis and change the ...
Charles B. Cameron's user avatar
2 votes

SNR simulation and "desired output signal"

Audio equipment have nominal output levels. Recorders, amps and mixing devices have also nominal input levels. It's either dBV or dBm to the nominal resistive load. Use that nominal level as your ...
unawriter's user avatar
2 votes
Accepted

SNR simulation and "desired output signal"

I see that audio equipment, like preamplifiers and audio recorders, always indicate their SNR in dB. But in relation to what output voltage? Well, the audio company marketing people will always try ...
Andy aka's user avatar
  • 443k
1 vote

How to create a PWM source with fixed frequency and decreasing duty cycle (at some interval) in LTspice?

I'm not exactly sure what you want to do, but I might have a way to accomplish it that is unproven. Look at the models for the LTC6993 (there are several with different features. They can do many ...
Voltage Spike's user avatar
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1 vote
Accepted

LTSpice (Berkeley Spice) Files. WHERE?

You get the models from either the manufacturer or another party that has modeled the device. It is possible in LTspice IV to create a new symbol from scratch for a third-party model but who has the ...
Voltage Spike's user avatar
  • 78k
1 vote

LTSpice (Berkeley Spice) Files. WHERE?

Tracking down and integrating SPICE models into a simulation is usually a bit of an adventure. There are many SPICE dialects and no standard. The model files are often proprietary and cannot legally ...
John Doty's user avatar
  • 2,525
1 vote
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Non inverting opamp with bias DC

You did nothing wrong. Just choose the value of your resistors R3 and R4 (My R9 and R10). Like this ...
Antonio51's user avatar
  • 11.9k
1 vote

How to measure flux in transformer in LTspice?

Which of these two expressions (if any) is correct and why is the other one (or both) wrong? Both are wrong... The flux in a transformer core is due to the magnetization current supplied by the ...
Andy aka's user avatar
  • 443k
1 vote

Discrepancy Between Bode Plot Predictions and FFT Output for Higher-Order Low Pass Filters on a 10 kHz Square Wave

Three of your plots have a 20dB/decade slope of the baseline, the three that went through your filter simulation. This baseline is obscuring what's happening to the harmonics, that will actually be ...
Neil_UK's user avatar
  • 162k
1 vote

Reverse polarity protection and inrush current limiting - back to back mosfets

These MOSFETS will be all the time ON since you need 0V between Gate and Source (0 Vgs) (not higher than -0.6V according to the datasheet) to turn them OFF. Which means, in this case, that the gate ...
Fredled's user avatar
  • 2,025
1 vote

The output of my rectifier which should be charging a capacitor on LTSpice is extremely jumpy and inconsistent

Assume capacitor is charged to Vp. During the period input sine wave is not at peak voltage neither diode conducts. This means both input lines are virtually open circuit looking from the capacitor ...
Kiymik's user avatar
  • 11

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