need help

need help - Messages

#1 Posted: 5/9/2026 8:35:16 AM
Andreas Beldowski

Andreas Beldowski

0 likes in 10 posts.

Group: User

Hello,

unfortunately, I can't find the error myself. Why VS(t) and VRG58(t) work well, but V1(t):=VS(t)-VRG58(t) not?

Regards Andreas

Auszug.pdf (114.69 KiB) downloaded 107 time(s).
Auszug.sm (16.52 KiB) downloaded 117 time(s).
#2 Posted: 5/9/2026 9:14:00 AM
sergio

sergio

122 likes in 340 posts.

Group: User

It seems that the two quantities have different units of measurement.
Solver_FXLZ2iLlqC.png
sergio
#3 Posted: 5/9/2026 12:44:41 PM
Andreas Beldowski

Andreas Beldowski

0 likes in 10 posts.

Group: User

Thanks Sergio,

wrong was VRG58(t):=Ig(t)*(1/ZLRG58+1/RRG58)

right is VRG58(t):=Ig(t)*(ZLRG58+RRG58)

Regards Andreas
#4 Posted: 5/10/2026 5:52:13 AM
Andreas Beldowski

Andreas Beldowski

0 likes in 10 posts.

Group: User

Hello,

and here’s another problem. Why does the differential of V1(t) work, but not that of V2(t)?

Both are sine functions; later, I’d like to try using square-wave functions as input as well.

For V1 and V2, I need the peak-to-peak amplitude and the phase difference between the two. I want to see if I can get better approximations for determining C1 by taking RG58 and the probe tip’s internal resistance into account in the measurement results.

Regards Andreas

Translation of “Der Wert ist oberhalb der maximalen Grenze für positive Zahlen” = “The value is above the maximum limit for positive numbers”

Versuch mit R und C mit Oszi.pdf (982.36 KiB) downloaded 85 time(s). The value is above the maximum limit for positive numbers.gif Versuch mit R und C mit Oszi.sm (131.13 KiB) downloaded 117 time(s).
Edited 5/10/2026 6:01:03 AM
#5 Posted: 5/10/2026 8:15:12 AM
StvMath

StvMath

44 likes and 1 dislikes in 71 posts.

Group: User

"Why does the differential of V1(t) work, but not that of V2(t)?"

It's a combination of the size of the numbers and the order in which SMath does its calculations. Try:

dV2dt.png
#6 Posted: 5/10/2026 10:41:34 AM
Andreas Beldowski

Andreas Beldowski

0 likes in 10 posts.

Group: User

Yeah, that's how it works for me, too.
#7 Posted: 5/12/2026 1:09:32 PM
Andreas Beldowski

Andreas Beldowski

0 likes in 10 posts.

Group: User

It's me again, with a new problem.

Why doesn't the last line work, when the four lines above it do?

Versuch mit R und C mit Oszi Auszug.gif Versuch mit R und C mit Oszi Auszug.pdf (910.43 KiB) downloaded 69 time(s). Versuch mit R und C mit Oszi Auszug.sm (130.35 KiB) downloaded 94 time(s).
#8 Posted: 5/13/2026 2:13:04 AM
Alvaro

Alvaro

1,106 likes in 1,782 posts.

Group: User

Hi. I have no idea why it fails, however this may be a workaround, consisting of directly applying the Newton-Raphson method.

image.png

Versuch mit R und C mit Oszi Auszug.sm (121.16 KiB) downloaded 85 time(s).

Best regards.
Alvaro.
#9 Posted: 5/13/2026 5:47:01 AM
Andreas Beldowski

Andreas Beldowski

0 likes in 10 posts.

Group: User

And why can I only use the values for LV1 and LV2 once, but the values for LdV1dt and LdV2dt multiple times?
I had already deleted the `clear()` statements, but that wasn't the problem.

Versuch mit R und C mit Oszi 3.gif
Edited 5/13/2026 5:48:52 AM
#10 Posted: 5/13/2026 9:41:38 AM
Alvaro

Alvaro

1,106 likes in 1,782 posts.

Group: User

Hi. Use eval:

image.png

Best regards.
Alvaro.
  • New Posts
  • No New Posts