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Spice Simulation Capacitor Initial Charge

shawn3WMTV
Enthusiast

Spice Simulation Capacitor Initial Charge

shawn3WMTV
Enthusiast
Enthusiast

Is there a way to set the initial charge of capacitors in the spice simulation? With LT Spice you just add IC=v to the spice line for the capacitor. I cannot find a way of doing something similar in Fusion.

 

 

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jorge_garcia
Autodesk
Autodesk

Hello @shawn3WMTV,

 

I hope you're doing well. Thanks for the post, there is a way to do this however or developers found a bug that breaks it.  It has been corrected and the fix will be out shortly. Once it comes out you'll be able to add that initial charge by using the SPICEEXTRA attribute.

 

So you can right-click on the component and select attributes. Create a new attribute called SPICEEXTRA it's value will be  IC=whatever_voltage_you_want_here

 

That's all you have to do.

 

Let me know if there's anything else I can do for you.

 

Best Regards,



Jorge Garcia
​Product Support Specialist for Fusion 360 and EAGLE

Kudos are much appreciated if the information I have shared is helpful to you and/or others.

Did this resolve your issue? Please accept it "As a Solution" so others may benefit from it.
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shawn3WMTV
Enthusiast
Enthusiast

I can see with the latest release the the attribute field can now be modified, but adding th IC attribute does not seem to have any affect. I this feature fixed in the latest release?

 

I am trying to simulate this oscillator. It needs a bit of a kick to get oscillating. In LT spice I just have to change the IC of C1. When doing the same in Fusion it has no affect and I get no oscilations. And if you probe the node where C1 is while changing the IC to different values, the simulation shows the volatge at the start of the simulation is unchanged.

 

shawn3WMTV_0-1708783833906.png

 

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jorge_garcia
Autodesk
Autodesk

Hello @shawn3WMTV,

 

That's the bug part I told you about. The attribute currently doesn't work because of it. It will be resolved shortly so just bear with us, the fix is coming.

 

Let me know if there's anything else I can do for you.

 

Best Regards,



Jorge Garcia
​Product Support Specialist for Fusion 360 and EAGLE

Kudos are much appreciated if the information I have shared is helpful to you and/or others.

Did this resolve your issue? Please accept it "As a Solution" so others may benefit from it.
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panpan_fan
Autodesk
Autodesk

Hi @shawn3WMTV 

We have released Fusion V2.0.19207
The issue you reported should be fixed now.
Please upgrade Fusion and try it again, thanks a lot!

Regards,

Panpan Fan

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