20
votes
Why doesn't the capacitor fill to the maximum?
You've likely exceeded dynamic range of CH1, making measurements untrustworthy.
Notice that the "zero" indicator for CH1 (lower left corner) is pointing down, indicating that the real zero ...
- 26.9k
20
votes
Accepted
Does switching on a bench power supply cause a voltage spike on its outputs?
It's quite difficult to get a circuit to have a clean behavior at power-on and power-off: filtered reference voltages may take some time to stabilize, opamps don't work properly until they get the ...
- 80.3k
20
votes
LTspice: simulating the bounce effect of a push button
You can use the rand() function to generate a noise-like signal, that combined with time and a bit of math and logic operators can produce something like switch bounce when used to control a ...
- 26k
16
votes
Accepted
LTspice: simulating the bounce effect of a push button
I'd suggest using a PWL voltage source. Convert that graph into a .txt file of time vs. voltage level, as accurate as needed. Then set the voltage source to use that PWL file as input. If you need ...
- 16.3k
12
votes
Accepted
I need to implement DC and transient analysis of diode and transistor circuits. How can I do that?
I strongly recommend that you get and read "The Designer's Guide to SPICE & SPECTRE" by Kenneth S. Kundert. The book covers every topic in which you are interested, and in detail. It ...
- 78.4k
12
votes
What is the physical model for energy flow in or around a lossless conductor during transient analysis? (Veritasium Electricity in Wires)
The video is very 'clickbaity', and in this sense has succeeded.
Unfortunately, the experiment presented is not well defined. The physical situation is very complicated. It depends on what assumptions ...
- 171k
8
votes
Does switching on a bench power supply cause a voltage spike on its outputs?
What Adafruit is recommending is powering up the supply, then plugging in the circuit? In other words, hot plugging.
A few years back we did a hot plugging test, powering up a 28 VDC supply then ...
- 1,389
7
votes
Accepted
Resistor in parallel with a short circuit. Will current flow through it?
If the short circuit is perfect, the two leads of the resistor are at the same Voltage potential. In that case, no current can possibly flow through the resistor, no matter how much current you run ...
- 2,858
7
votes
Transmission Line Transient Response To Step Voltage Prior To Any Reflections
I am specifically asking whether the driving circuit will see the
transmission line as a pure resistance according The Telegrapher's
Equations, or whether those equations predict the driving circuit ...
- 87.1k
7
votes
What is the time constant for this circuit?
Why is the 10k resistor ignored?
It doesn't affect the time constant because the "-" terminal is a virtual ground, so its voltage doesn't vary.
However, it is not ignored, since its value ...
- 23.9k
7
votes
What is the physical model for energy flow in or around a lossless conductor during transient analysis? (Veritasium Electricity in Wires)
Electroboom gets it right (new posting.)
https://www.youtube.com/watch?v=iph500cPK28
This is non-controversial, utterly simple RF design knowledge ...when it's only occurring over a fraction of a ...
- 11k
6
votes
Transmission Line Transient Response To Step Voltage Prior To Any Reflections
I am specifically asking whether the driving circuit will see the
transmission line as a pure resistance according The Telegrapher's
Equations, or whether those equations predict the driving circuit ...
- 466k
6
votes
Accepted
Buck converter load current step response
The output impedance of the buck converter operated in open-loop (no feedback) can be rearranged with a leading term representative of the resistance at dc (when the capacitor is open and the inductor ...
- 23k
5
votes
Accepted
At t=0 the voltage across the Inductor will immediately jump to battery voltage. Why?
Switch closes. Electric field starts to propagate in the wire, much faster than electrons.
Maxwell equation number 4 says:
The magnetic field induced around a closed loop is proportional to the ...
- 952
5
votes
What is transil and how it works?
Transil is a trademark from ST for its TVS diodes. TVS diodes behave somewhat like zener diodes: the current flows through them as soon as the voltage exceeds a given value. Contrary to Zener diodes, ...
- 1,745
5
votes
Accepted
AC analysis on transient model of Buck converter
AC analsyis (in the sense the term is used in SPICE) assumes all components in the circuit are linear.
A buck converter only works if some components (the switches) operate nonlinearly.
Therefore, ...
- 132k
5
votes
Accepted
LC Circuit LTSpice Simulation With Time Switch
Left click on .ic V(n001)=0.2107 I(L1)=0 and make sure the text is a SPICE directive.
When it is a Comment, you get the output as shown in OP.
Shown below is an ...
- 10.8k
5
votes
Accepted
Very short rise and fall time with relay
Unfortunately this isn't really a mechanical problem and has little to do with the relay itself.
A mercury-wetted relay is certainly the right choice, but their contact closure speeds are a couple ...
- 29.1k
5
votes
Reverse voltage spike protection on high-side of a (coiled) relay without flyback diode
The 12V is connected to the 3V regulator out. That will instantly destroy the MCU.
You cannot switch a 12V p-channel MOSFET with a 3V output. It will stay on all the time (since Vgs = -9V and it ...
5
votes
Short-circuit current through disconnected capacitor
What you are asking is very complicated. Looks easy enough until you realise that you are connecting a 0Ω resistor across a voltage source. The current you would get if that 0Ω was ideal, and the ...
- 42.1k
5
votes
Purpose of reverse biased diode in pulse generation circuit
But what is the purpose of the diode shown in the schematic?
When the output of the first Schmitt trigger goes high, the cap develops a voltage across it. When the output of the Schmitt subsequently ...
- 26.1k
5
votes
Does switching on a bench power supply cause a voltage spike on its outputs?
Yes, of course there can be a glitch.
It does not mean there is a problem with all power supplies.
So that warning may look like absurd but if you have ever fried something and don't know what caused ...
- 164k
5
votes
Accepted
Energy in capacitor paradox
however if you put this on a SPICE simulator with the initial conditions and a load of R=25k, you will see that it fully discharges.
No, it does not fully discharge, depending on what you call the '...
- 171k
5
votes
Accepted
Is there an equation to calculate the voltage spike caused by an inductor in the absence of a freewheeling diode?
The voltage at the drain when the MOSFET turns off depends on the peak current \$I_p\$ and the capacitance lumped at that node. Provided the breakdown voltage is high enough, the voltage will peak to ...
- 23k
4
votes
Accepted
H-bdrige inverter: unkown transient
Do you know where does the transient come from?
I don't see what you call a "transient".
Did I choose the right transistor to achieve what I want?
Since you tell nothing about intended load, ...
- 80.3k
4
votes
How Fourier transform be able to deal with transients?
Check out any reference on Gibbs phenomenon. It essentially says that the Fourier series cannot fully accurately represent any repetitive signal with discontinuities. What one gets when the series is ...
4
votes
Accepted
Using Fourier transform to solve current in a circuit with initial condition
First of all, the Laplace Transform and the Fourier Transform spring forth from the same body of water. They are sorta the same thing, and if you have common conditions using either, they are the ...
- 1,695
4
votes
Have 'natural response' defined clearly?
There are two possible ways of splitting the system response for analysis:
a) Transient vs Permanent response
b) Natural (zero input) vs Forced (zero state) response
Part of the transient comes from ...
- 333
4
votes
Accepted
Why do we use Laplace transforms to analyse transient circuits?
It's easy to solve simple filter circuits in the time domain but there becomes a tipping-point where most engineers would prefer to solve problems in the frequency domain and apply (for example) a ...
- 466k
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