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I had a sim would not resolve. "Timestamp has fallen..."

On re-entering I realized I had entered C1 as "-0.5u"... negative!

The font used on my installation makes this very hard to see.

While a negative capacitance has some meaning in theory, in context of PSDU users this is almost certainly a finger-fumble.

I dunno if it is worth adding a sanity/censor-check to refuse negative caps. I have been using PSDU for a decade+ and I think this is the first time I made this screw-up.

Hmmm, negative resistor---- ah, it accepts the input then blows-up at 5,102V. Which is probably correct: the neg-resistor is powering the circuit, just as neg-R repeaters power-over telephone line loss.

This sounds quite bizarre, I'm fairly sure I would have put some minimum and maximum limits on values to prevent "issues" so it's quite odd that negative values can go in. Could you please let me have the following:

• Reply to the email with a screen dump, or the .psu file so I can have a look
• Details of the build number from Help | Abpout
• Details of the OS you're using

In the interim, I'll have a look at this end to run some checks. Thanks very much.

Regards,
Duncan

Screen capture showing values and plot, .psu file, About screen, Windows properties screen.

Hi Paul,

Thanks for sending the screen dump and other info. I've had a look in the file you sent, and the value in there is definitely -1E-6 (-1uF). However, I cannot offer any kind of explanation as to how it got in there.

I've checked the code back as far as I can, there is version control back to 2011, and even back then there was a minimum value for a capacitor which should prevent a negative value being keyed in.

I'm working on Build 78 here which is slightly newer than your version, but there are no heavyweight changes between the two. I'm unable to duplicate the problem or key in a negative value no matter how I try. That's probably not a helpful answer, but I'm out of ideas on what might be wrong.

Regards,
Duncan

a minimum value for a
capacitor which should prevent a negative value being keyed in.

'When' is the check?

I am not sure I can do this on initial setup. I seem to do it at-will by editing an existing setup. Transformer voltage dialog objects to <2V at first setup, but if I enter 2V then click again to edit, it accepts backspace dash (leading minus sign). It may *later* throw floating-point or other error, but a re-edit negative is accepted and often runs. (Often enough that I did not immediately suspect fumble-finger.)

It *may* depend if I OK out of the dialog by mouse-click or by TAB to the OK button and Enter. Not sure of this, and I have to take the car for inspection today....


On 11/7/2022 12:47 PM, Duncan Munro wrote:

Subject:
Re: [duncanampspsud] Negative capacitor?
From:
"Duncan Munro" <duncan@...>
Date:
11/7/2022, 12:47 PM
To:
[email protected]
Hi Paul,
Thanks for sending the screen dump and other info. I've had a look in the file you sent, and the value in there is definitely -1E-6 (-1uF). However, I cannot offer any kind of explanation as to how it got in there.
I've checked the code back as far as I can, there is version control back to 2011, and even back then there was a minimum value for a capacitor which should prevent a negative value being keyed in.
I'm working on Build 78 here which is slightly newer than your version, but there are no heavyweight changes between the two. I'm unable to duplicate the problem or key in a negative value no matter how I try. That's probably not a helpful answer, but I'm out of ideas on what might be wrong.
Regards,
Duncan

'When' is the check?

The checking is done when you try and exit the box containing the value. For example, if you key in -1u then nothing happens until you try and move. Pressing tab or clicking on the OK button will cause the field exit checks to be carried out.?

However... I've found out how it's been happening though as I can now reproduce the problem:

• Exit the box by pressing Tab - Throws an error - CORRECT
• Exit the box by clicking the mouse - Throws an error - CORRECT
• Exit the form by pressing Enter - Accepts any old rubbish - INCORRECT RESPONSE

I'll put it down on the log as "needs fixing", thanks for letting me know.

Regards,
Duncan

On 11/7/2022 2:09 PM, Duncan Munro wrote:

on the log as "needs fixing"

JUST after I saw your reply, I was on The Register.com ' Oops~ column, and saw this comment:

"Bug reports are a Good Thing for software that people find useful: it's a sign that people are using it (and quite probably for things you didn't envisage)!"

article:
comment:

Thanks for looking at this.