6
votes
Accepted
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 ...
- 8,429
5
votes
Accepted
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.
- 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 ...
- 78k
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. ...
- 383k
5
votes
Accepted
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 ...
- 1,457
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 ...
- 3,921
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 ...
- 2,525
3
votes
Accepted
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 ...
- 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 ...
- 30.2k
3
votes
Accepted
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 ...
- 443k
2
votes
Accepted
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 ...
- 3,849
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
...
- 71.9k
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, ...
- 137k
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:
...
- 14.1k
2
votes
Several base current values on the same graph
You can .dc a current source into the base and plot the collector current:
- 19.6k
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 ...
- 20.7k
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 ...
- 25.7k
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 ...
- 30.2k
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 ...
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 ...
- 21
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 ...
- 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 ...
- 78k
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 ...
- 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 ...
- 2,525
1
vote
Accepted
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 ...
- 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 ...
- 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 ...
- 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 ...
- 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 ...
- 11
Only top scored, non community-wiki answers of a minimum length are eligible