Hello, I want to obtain the amplitude of the LC circuit while oscillating at natural response. I am new to this so I am unable to get it. I have performed a transient analysis of LC circuit by providing step input in ltspice and now I want to obtain the amplitude at which the circuit is oscillating at natural frequency. Can you guys please help me out with it.

 

hi 12,
Welcome to AAC.
Please post your LTSpice asc file so that we can run it.
E

 

hi 12,
Welcome to AAC.
Please post your LTSpice asc file so that we can run it.
E

Thank you eric,
I have added the asc file. Please take a look

 

hi,
Do really mean 1Henry and 200Farads.??
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hi,
Do really mean 1Henery and 200Farads.??
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Not exactly. I have converted a mechanical system into its equvivalent analogous electrical system. So the inductor is 1H and capacitor is 0.005F. Sorry I forgot to change the capacitance

 

hi,
Is this what you are seeking.?
E

 

I can see the amplitude in this waveform. But I want the amplitude on a certain node so that when I export the netlist i can obtain the amplitude. from that node.
Did you understand my question?
I am bad at explianing sorry.

 

hi,
On that circuit there are only two nodes, n001 and n002, both waveforms are on the posted plot image.

I don't fully understand what you are asking, could you give an example?
E

 

When I export the netlist, I will have the nodes and voltage sources but not the voltage at node n002. I need that to be written onto the netlist.

 

Have looked thru LTS and I cannot see a way to add that Vn002 to the netlist.
Never had a reason to do so.
Perhaps @Bordodynov may have a method.

E

 

You can use the .MEASURE command to get the amplitude, but the answer appears in the Error Log, not the Netlist.

 

Actually I am working with ANSYS and LTSPICE together. I want to import the values from LTSPICE and provide the amplitude as input in ANSYS.
Thank you for your time Eric

 

You can use the .MEASURE command to get the amplitude, but the answer appears in the Error Log, not the Netlist.

Hi Alec_t , Can you tell me more. how can we get it in the error log? what command to use

 

You can use the .MEASURE command to get the amplitude, but the answer appears in the Error Log, not the Netlist.

hi alec,
Already done that, but TS wants it auto listed in the netlist.

Directive .meas V(n002)
v(n002)= 1 from 0 to 1
Eric

12, Use .meas V(n002) then View Error log

 

hi 12,
I guess you know that a real Inductor will have some resistance value, if you make it 1R, the damped response is as per this plot.
E

 

Thanks, But it didnt solve my problem. I cannot add a resistor to the circuit as I want the sinusoidal wave itself and not damped wave

 

See