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I think you have misunderstood. You can put a 10f (femtofarad) cap in an .ASC by writing that value in the component property pane. Try it: feed a 10f cap via 1meg and the -3dB point is at 16MHz.

Yes, I agree, on all counts. It means Farads, in lower OR upper case.

But in the .options context, it appears to accept 10f as 10 femtofarads.

That’s logical, because who would want a 10F parasitic shunt capacitance?

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I’m just disturbed that it’s different, between contexts.

Not much different from ^ vs. **, where the carat could mean exponentiation or exclusive OR

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From: [email protected] <[email protected]> On Behalf Of John Woodgate
Sent: Monday, February 24, 2025 2:03 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] intuition behind a solution to crashing time domain simulation #Time-step-too-small

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I think that 10 means 10 farads, 10m means 10 millifarads etc, but, with a space in between, 10 f or 10 F or 10 m means 10 farads and the following letter is disregarded, or throws an error in some cases. This works in the component properties pane.

On 2025-02-24 21:52, Bell, Dave via groups.io wrote:

In *this case*, I see that.

Seems like a bit inconsistent…

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From: [email protected] <[email protected]> On Behalf Of John Woodgate
Sent: Monday, February 24, 2025 1:36 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] intuition behind a solution to crashing time domain simulation #Time-step-too-small

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10f is recognized as 10 femtofarads.

On 2025-02-24 21:29, Bell, Dave via groups.io wrote:

Is “10f” a special case in the parasitics settings?

For a regular cap, it would mean 10 Farads!

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From: [email protected] <[email protected]> On Behalf Of john23 via groups.io
Sent: Monday, February 24, 2025 12:29 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] intuition behind a solution to crashing time domain simulation #Time-step-too-small

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The following line solved the problem.Is there some manual or intution regarding why these might help?

.options cshunt =10f gshunt=10n abstol=10n vntol=1m

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Thanks.

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Virus-free.

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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