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Re: Simulating Using PyLTSpice Takes Too Long
Help? me understand the problem.
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<davitkharshiladze26@...> wrote:
Is 1 second too much time and that is what you want to reduce?
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Or is 1 second small, and adding PyLTspice causes the total time to be much greater than 1 second?
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Andy
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Re: Conductance Negative
On Sat, Mar 29, 2025 at 05:41 PM, alan victor wrote:
I might be wrong, but I think alan is referring to one of the example schematics that installs on your computer's disk when you install LTspice.
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...\examples\Educational\Colpitts.asc
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Andy
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Re: Conductance Negative
On Fri, Mar 28, 2025 at 11:53 AM, <sebastian.herrera@...> wrote:
Dear all, I am trying to simulate a circuit with negative conductance using transistors and passive components. Does anyone have a circuit for this?Use the educational examples, oscillators, Colpits and remove the resonating inductor leaving the active device and passive feedback? elements in place. Do a scattering parameter operation and note the modulus of S11 is > unity over the range of potential frequency
of operation. This yields negative conductance. Note there is a nice peak in negative G value in the 1-10 MHz range and extends out to ~ 40 MHz.? |
Re: Simulating Using PyLTSpice Takes Too Long
LTSpice generates .raw output files, noramlly.
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I am using PyLTSpice tp prepeare netlist before simulation. I am manually writing the netlist.
After simulation, I am gathering .raw files and reading info from them.
I also use PyLTSpice to directly run the simulation after the netlists are prepeared:
? ? ? ? t1?=?time.time()
? ? ? ??LTC.run(netlist=netlist_filename)
? ? ? ??LTC.wait_completion()
? ? ? ??print(f"{t1?-?time.time()}?- Simrun")
LTC.run runs the simulator and LTC.wait_completion() waits for .raw generation to finish. Afterwards i can read these files for my desired outputs.
The runtime of these 2 functions are approximately 1 second, which is way too much for my purposes.
I feel like normal LTSpice simulation takes about the same time, though, as I mentioned, it is harder to measure |
Re: Simulating Using PyLTSpice Takes Too Long
Unfortunately, I can not use .STEP command.?
My main problem is finding multi-port s-parameters of a given circuit. LTSpice only supports 2-port s-parameters. To measure 4-port s-parameters I need to run simulation several times (6 times to be exact), where I change the port locations on each iteration. This requires me to slightly modify the netlist, meaning that I am running practically new simulation each time.
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Even when I run simulaiton using LTSpice it still takes approximately 1 second, thought, it is harder for me to measure, therefore, I feel the problem is within the simulator itself. I feel like the simulator needs time for initializing, file writting and so on. I have not found a way to disable any additional protocols.
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Thank you for your responses? |
Re: Simulating Using PyLTSpice Takes Too Long
¿ªÔÆÌåÓýI made the schematic in LTspice and it runs very fast. The netlist is: * C:\Program Files\ADI\LTspice\Draft1.asc The .ASC is just temporarily stored with that
path, because I have not Saved it. On 2025-03-29 20:45,
davitkharshiladze26 via groups.io wrote:
--
OOO - Own Opinions only If something is true: * as far as we know - it's science *for certain - it's mathematics *unquestionably - it's religion |
Re: Simulating Using PyLTSpice Takes Too Long
I have no familiarity with PyLTspice.? But you say most of the time is spent doing something other than the LTspice simulation itself.? Which means the cause is something other than LTspice.
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Maybe there's another way to automate your sims which doesn't use this particular slow Python code, which seems to be the bottleneck.
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.AC simulations can be quite fast and there's very little dependency on the sweep parameters.? That's because .AC analysis is 100% linear, once the operating point is found.? The sweep requires no iterations and no convergence issues.? It's fast.
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Contrary to what eT wrote, I think your netlist is fine and without problems.
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Andy
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Re: Simulating Using PyLTSpice Takes Too Long
On Sat, Mar 29, 2025 at 12:42 PM, <davitkharshiladze26@...> wrote:
You can confirm the netlist format by simulating it directly in LTspice without using python. It won't run correctly formatted the way you've shown.
See my previous post.
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Re: Simulating Using PyLTSpice Takes Too Long
try the developer.?
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Re: Simulating Using PyLTSpice Takes Too Long
The circuit may have some unreasonable problems, however, I am not plotting anything, nor am I trying to obtain any meaningful data from this circuit. This is a dummy circuit that represents the problem that my original meaningful circuit had. I can not share my original circuit.
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Changing frequency sweep keeps the simulation runtime the same. Changing the format of stimulus does not make any change either. |
Re: Simulating Using PyLTSpice Takes Too Long
¿ªÔÆÌåÓýI see. but there are problems with this simple
circuit. Using a linear sweep with such a wide range doesn't
result in a useful frequency response plot. A decade sweep is
much better. Also, the 50 ohm load damps the resonance at 48 MHz
so much that it cannot be seen on the plot. On 2025-03-29 19:25,
davitkharshiladze26 via groups.io wrote:
--
OOO - Own Opinions only If something is true: * as far as we know - it's science *for certain - it's mathematics *unquestionably - it's religion |
Re: Simulating Using PyLTSpice Takes Too Long
On Sat, Mar 29, 2025 at 12:01 PM, <davitkharshiladze26@...> wrote:
The first line of a spice netlist file is a comment line and is not read. This is standard for a spice netlist.
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V1 N001 0 AC 1 ? <---this "stimulus" line is not being read. Insert a blank line before this line.
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Also, the stimulus line should really look like this:
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V1 N001 0 DC 1 AC 1
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The AC parameter will override the DC parameter for an AC analysis.
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eT
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