I wrote:

Perhaps a Pi-source?

I meant to write Bi-source.? In other words, a B-source with I=<value>.? You can get fancy where the I depends on its voltage, thus turning it into a controllable resistance.? That's one of many ways to do it.

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Andy

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On Sat, Mar 15, 2025 at 11:26 AM, john23 wrote:

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Hello ,I am trying to test a voltage regulator by re[lacing a steady resistor with some sort of varying resistor.

Given the circuit in the attached Zip file , what kind of "resistor" you reccomend?

/g/LTspice/files/Temp/regulator.zip

Your uploaded files have very little information.

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Is the "regulator" the 3-transistor circuit, with R4 being the load at the regulator's output?

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Can you? describe how you want the load to vary?? Do you know what you want it to do, or do you just want it to be random?

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Can you describe it mathematically using a B-source?? Perhaps a Pi Bi-source?? That should lead you to what you should try.

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Andy

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Hello ,I am trying to test a voltage regulator by re[lacing a steady resistor with some sort of varying resistor.

Given the circuit in the attached Zip file , what kind of "resistor" you reccomend?

Thanks.

Hello to all,

I just discovered the discussion.

I would be very interested by the SOATherm simulation.

I found it crazy that this is almost unusable as there is almost no documentation on it.

Does anyone have any news ?

Thanks a lot in advance.

On Sat, Mar 15, 2025 at 02:09 AM, <mhx@...> wrote:

I'm curious as to why you want to (inaccurately) do this in the s-domain?
Your equation is available in the time domain, and it perfectly fits
the way of working of the EXP() voltage source:
Vxxx n+ n- EXP(V1 V2 Td1 Tau1 Td2 Tau2).

-marcel

Hello, Marcel:

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At first, it's the ideal in sketch the applied circuitry in s-domain on how to attenuate the surge amplitude. Sometimes, in math domain, possibly solutions will be clear to see, though not everytime.

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Some reasons else maybe:

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1. For fun to see more ways to implement on simulator.

2. Curiosity the capability of LTspice's Laplace.

3. Puzzle for group ? (puzzle or not , not sure.)

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Thank you , wish you happy and healthy.

after simulation, i do the following:

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e.g. on a resistor R1, holding alt button and hovering over the element R1 shows in the status bar "Left-click to plot R1 dissipation: ...".

but doing so, does not add any plot.

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other than manually typing and adding the plot, is there a correct way for the same. or am i doing something wrong here?

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thanks.

Hi, Tony, Andy:

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Thank you for your opinions and sharing files.

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The file uploading issue was not about technical, it's about company policy, they will log the uploaded files, and trace the content maybe (I am not sure what detailed will be done.)

So that, the picture is not about 'confidential material' it's public knowledge, no 'confidential issue', but *.asc, I am not so sure, any insignificant thing could damage huge, says 'A single spark can start a prairie fire'.

Just to avoid any suspect.?

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In fact, the main concern of this topic is about the s-equation, if you have ran the simulation , you will see the amplitude of time domain is about 5KV, but only? 40mV in the s-domain, though the s-equation was surely correct by matlab or ChatGPT by doing laplace tranform from its time's.

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If you have any idea, why their output are different, please kindly share some opinions.

(Is it bug or something else .... ? After some time, I presume the initial condition of the voltage should be 0V same as time-domain....., the different is the scale mV vs. KV...)

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Thank you very much.

Best regards.

On Fri, Mar 14, 2025 at 02:32 AM, <ericsson.sunshine@...> wrote:

Then since I can't upload the file , (the policy of ... some confidential reason, though I don't know what needed to be confidential), I beg your pardon, please allow me to paste the .asc content in the tail if this thread.

I uploaded your file for you, in "IEC_61000-4-2_Surge_6KV_ericsson_sunshine.asc" in the Temp folder.

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It is curious that you can upload a Photo but not a File.? Does groups.io actually allow one but block the other?? What is the message you see when attempting to upload a file?

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Tony uploaded "IEC_61000-4-2_Test.zip", but it has a symbol that LTspice might not have and can't be opened in older versions.

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Andy

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Hi, :

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May I ask a question about to generate the surge waveform using time equation & s-equation, on how to do that in LTspice ?

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For example, I asked the ChatGPT, about the 6.0KV surge waveform of time domain, then same as the s-domain equation, but I don't quite know how to express the s-equation exactly. I presume maybe some initial condition needed to be given, but brain twisted. And not sure if that's supported in BV's laplace expression, often it's for transfer function. In the following, it shows the equation for time & s as well.

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Then since I can't upload the file , (the policy of ... some confidential reason, though I don't know what needed to be confidential), I beg your pardon, please allow me to paste the .asc content in the tail if this thread.

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Have a nice day. Thank you very much.

Best regards.

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the image about equation description here. (I don't know how to insert picture correctly here, it said me don't have the privilege.)

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Version 4
SHEET 1 1120 680
WIRE 0 112 0 96
WIRE 192 112 0 112
WIRE 672 112 672 96
WIRE 864 112 672 112
WIRE 0 208 0 192
WIRE 192 208 192 192
WIRE 672 208 672 192
WIRE 864 208 864 192
FLAG 0 208 0
FLAG 192 208 0
FLAG 0 96 V_time
FLAG 672 208 0
FLAG 864 208 0
FLAG 672 96 V_s
SYMBOL bv 0 96 R0
WINDOW 3 -274 178 Left 2
SYMATTR InstName B1
SYMATTR Value V=6000*( ?exp(-3.5e6*time) - exp(-0.14e6*time) ?)
SYMBOL res 176 96 R0
SYMATTR InstName R1
SYMATTR Value 1
SYMBOL bv 672 96 R0
WINDOW 3 -274 178 Left 2
SYMATTR InstName B2
SYMATTR Value V=1*u(time) laplace=6000*( 1/(s+3.5e6) - 1/(s+0.14e6) )
SYMBOL res 848 96 R0
SYMATTR InstName R2
SYMATTR Value 1
TEXT 148 -90 Left 2 !.tran 200u startup

Hi.

The ferrite you specified is low-frequency. There is a Fe - Feddy parameter in my model. ?As the frequency increases, the magnetization reversal loop expands. See the file NonLinearTransformer_pulse_AB3.zip in the TEMP folder.

jad700,

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I just uploaded "LTspice_TableTest_AI.zip" to the Temp folder.? It corrects your Bv source with the Table() function, and it shows that it works to refer to the voltage V(SET) instead of a fixed parameter, as the index to the table's values.

?

Andy

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Oops, I had an extra "V=" in my reply.? Should be "V=Table" not "V=V=Table".

On Thu, Mar 13, 2025 at 09:50 PM, <jad700@...> wrote:

Hello? ... I need a BV source to use a TABLE to look up a response.? This works if the controlling variable is a .param ( Static for the full sim)? but I need the BV to be dynamic ( Use the TABLE lookup in response to a changing voltage and respond with the voltage result )? I have tried to do this, but no success yet.? I uploaded? LTspice_TableTest.zip to the temp folder.? Thank you so very much for any help you can provide!!? JD

1. Fix the Table() function.
   1. In your example, it is short enough so you could paste all the values into the Table() function itself.
2. Verify that it works using parameter {KK}.
3. Change the index parameter from "{KK}" to "V(SET)".
4. Verify that it still works.

B1 OUT 0 V=Table(V(set),

.inc table_R1.txt

The bottom ?of the E source IS the common mode input.

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