Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
I think the word "out" used here refers to bringing the net or node from inside to outside the subcircuit.
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Andy
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
I think "plumbing out" here means similar to "routing out" or "bringing out".? Connecting.
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Andy
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
OK. Still I don't understand the meaning of "plumbing out". Is it
meant to replace "disconnect"?
Le 05/02/2025 à 06:23, Andy I via
groups.io a écrit?:
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On Wed, Feb 5, 2025 at 12:07 AM, Jerry Lee Marcel wrote:
But I still fail to understand the relevance to
ground.
I think eewiz now made
it clear there that wasn't any relevance to ground.? That
was something going through my mind, and I guessed wrongly.? I
was imagining a plumb-line, which takes the shortest, most
direct path straight to earth.
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For eewiz, the comparison was to plumbing, by routing the
Node 0 signal out of a subcircuit.
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Andy
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
On Wed, Feb 5, 2025 at 12:07 AM, Jerry Lee Marcel wrote:
But I still fail to understand the relevance to ground.
I think eewiz now made it clear there that wasn't any relevance to ground.? That was something going through my mind, and I guessed wrongly.? I was imagining a plumb-line, which takes the shortest, most direct path straight to earth.
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For eewiz, the comparison was to plumbing, by routing the Node 0 signal out of a subcircuit.
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Andy
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On Wed, Feb 5, 2025 at 12:00 AM, Bell, Dave wrote:
I didn’t find the 33V Zener in the library maybe a typo.
In my installation, BZX84B33VLY is built-in.? I wonder if Analog Devices removed it from the library in your version?? You did not make a typo with that.
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Andy
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
Le 04/02/2025 à 23:45, Tony Casey a écrit?: I'm surprised no one has worked with the origins of plumb. I have. Being french, I have no merit. The french name for lead is plomb. But I still fail to understand the relevance to ground. I understand the analogy between current flow and circulation of fluids, though. In particular "plumbing out"...
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Ahh, thanks, Andy!? Too many (well, one main one) assumptions.
I didn’t find the 33V Zener in the library maybe a typo.
I couldn’t read the reference diode’s part number, so made a not too unreasonable guess, considering its purpose.
The value of (my term) Rpot was only 0.1 ohm in the photo, so I made a guess at the expected Vout.
3V would have been a better guess, given my ass-u-med Vz.
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Dave
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From: [email protected] <[email protected]>
On Behalf Of Andy I via groups.io
Sent: Tuesday, February 04, 2025 8:50 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Dual Power Supply
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I don't know if you didn't see this before?
The BZX84B33VLY is a 33 V zener.? It is very unwise in my opinion to re-define it as a 3.3 V zener.? The power supply's intended output is +/- about 30 V, so that will not work.? It might 'let out the magic smoke'.
In your simulation, those zeners are in breakdown!? The regulated outputs exceed 3.3 V, turning ON those "protection" zeners.? That's not right.? (That may be why the simulation crawls.)
Not only that, but you created a conflict between LTspice's built-in BZX84B33VLY model and your modified "AKO" model.? Dangerous!
Also the reference diodes in the original circuit had a voltage of around 1.24 V, not 0.68 V.
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Dave,
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I don't know if you didn't see this before?
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The BZX84B33VLY is a 33 V zener.? It is very unwise in my opinion to re-define it as a 3.3 V zener.? The power supply's intended output is +/- about 30 V, so that will not work.? It might 'let out the magic smoke'.
?
In your simulation, those zeners are in breakdown!? The regulated outputs exceed 3.3 V, turning ON those "protection" zeners.? That's not right.? (That may be why the simulation crawls.)
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Not only that, but you created a conflict between LTspice's built-in BZX84B33VLY model and your modified "AKO" model.? Dangerous!
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Also the reference diodes in the original circuit had a voltage of around 1.24 V, not 0.68 V.
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Andy
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Hello All:
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On Mon, Feb 3, 2025 at 10:45 PM, Andy I wrote:
By the way, I am not sure if everyone here understands your use of the words "plumb" or "plumb out".? Honestly, I am not sure that I know exactly what you mean either.? Remember that a sizable percentage of?the members of this group are not in North America and do not know our slang.
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From the Meriam Webster Dictionary
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plumbing
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: an internal system that resembles plumbing especially
: one consisting of conduits or channels for conveying fluids
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On Mon, Feb 4, 2025 at 4:43 PM, mstokowski wrote:
: to supply with or install as plumbing
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intransitive verb
: to work as a plumber
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All for now
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Re: In need of some zeners or maybe model them myself
On Tue, Feb 4, 2025 at 08:30 PM, Ivan wrote:
Funny that it just dawned on me that it doesn't matter if the model is for a through-hole or an SMD. That is the case, no?
Correct.
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The majority of SPICE models for components not used at very high (UHF+) frequencies do not have parasitics (R, L, C) for package leads or how they are mounted to the PCB.? If you were simulating at high enough frequencies, it matters.? Otherwise it is usually ignored.? If the model has those parasitics, they would need to be .SUBCKT models because .MODEL models can't include lead/pin inductance.
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Unless there's something in the LTSpice programming that recognizes whether it's an SMD or a through-hole device and as such, will treat the model differently but..., that's not the case, correct?
Correct.? It simulates only what it is explicitly told to simulate by the user running the simulation.? If you want to include lead/pin/mounting parasitics, most likely you need to add them yourself.? RF device models might include them already.? SPICE models are text so you can read them and know what they have.
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I am right in assuming therefore that, as long as the model parameters match the datasheet, and therefore the device I'm trying to model, I'll be golden, yes?
Tough question.? Simulations are never quite correct, but good models should yield good results in most cases.? There can be exceptions, though, so being 'golden' is never guaranteed.
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If you can verify the models, by comparing them not just with the datasheets but with other measurements of real parts, you are usually in good shape.? Comparisons with datasheets are pretty good; going further (if you can) gives you better confidence.? Many SPICE users don't do either.? Sometimes they are lucky, sometimes not.
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Andy
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Re: In need of some zeners or maybe model them myself
On Tue, Feb 4, 2025 at 07:37 PM, Ivan wrote:
Where did you upload them to? I looked in files but, don't see anything called "some-zener-model.zip"
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The Files " Temp" folder is almost always the place to look first for newly-uploaded files. ?
Andy
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Re: In need of some zeners or maybe model them myself
On Tue, Feb 4, 2025 at 07:04 PM, Mike Fraser wrote:
Ivan,
Central Semiconductor has spice models for 3.3V and 11V zener diodes.
You should go to their web site and download the spice models and data sheets.
You will need to evaluate and determine the suitability of the models.
CMPZ5226B.LIB and CMHZ4698.LIB.
Mike
Grabbed them and several others as well. Funny that it just dawned on me that it doesn't matter if the model is for a through-hole or an SMD. That is the case, no? Unless there's something in the LTSpice programming that recognizes whether it's an SMD or a through-hole device and as such, will treat the model differently but..., that's not the case, correct? I don't know, hence why I'm asking. Having said that, I am right in assuming therefore that, as long as the model parameters match the datasheet, and therefore the device I'm trying to model, I'll be golden, yes? Either way, I think these will be close enough to get me started. Now I just got to figure out how to translate some of the parameters in the model to their equivalent datasheet specs. Most of them I know but, not all. Research time again. Lol! Please let me know if I'm right about all that and..., thanks.
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Re: In need of some zeners or maybe model them myself
On Tue, Feb 4, 2025 at 04:11 AM, John Woodgate wrote:
Which country are you in? I know of a British supply of the power transistor at a very low price, comparatively, but not for export.
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USA but, I'm not looking to get any. We have a supplier at work. Don't know who and don't care what they cost. Not my circus. Just looking for the spice model. In your first response you said " Then ask the manufacturer, found by a web search - STI in the case of the 1N4572, Microchip for 1N5226, etc.". You're not implying that you found spice models on their sites are you? I haven't been able to get anywhere on either site.
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
Did someone say short? What are the real and virtual impedances?
No real grounds; no real shorts. (JMNSHO)
Donald.
On 2/4/25 19:13, Bell, Dave via
groups.io wrote:
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And if the
weighted line is too short at 12 feet, do we shout, “mark
TWAIN”?
?
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Which leads us to plumb the depths of the language issues
with a lead-weighted line, with which we might find a true
ground.
(FWIW, I don't believe in "ground" - most nodes labelled
"ground" are actually nets that return current to some
reference node.)
Donald.
On 2/4/25 17:45, Tony Casey wrote:
I'm surprised no one has worked with the
origins of plumb. Plumbum is the latin name for lead (hence
the chemical symbol Pb). The English word "Lead" is, of
course,? a heteronym - a multi-functional word with
different pronunciations.
--
On 04/02/2025 22:46, John Woodgate
wrote:
The only things that you can plumb in
English are 'the depths'.
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Re: In need of some zeners or maybe model them myself
On Tue, Feb 4, 2025 at 03:52 AM, Abes wrote:
Hi Ivan,
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I've uploaded a zip file - some-zener-models.zip - with 2 files in it. The Cordell text file I might have downloaded from here, can't remember.
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The 1N5241B is in both files. There may be some equivalents you can use.
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--
--
Regards,
Abes
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Where did you upload them to? I looked in files but, don't see anything called "some-zener-model.zip"
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
And if the weighted line is too short at 12 feet, do we shout, “mark TWAIN”?
?
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From: [email protected] <[email protected]>
On Behalf Of Donald H Locker via groups.io
Sent: Tuesday, February 04, 2025 4:02 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Any Good Reason to Plumb Ground Out of Hier. Schem.
?
Which leads us to plumb the depths of the language issues with a lead-weighted line, with which we might find a true ground.
(FWIW, I don't believe in "ground" - most nodes labelled "ground" are actually nets that return current to some reference node.)
Donald.
On 2/4/25 17:45, Tony Casey wrote:
I'm surprised no one has worked with the origins of plumb. Plumbum is the latin name for lead (hence the chemical symbol Pb). The English word "Lead" is, of course,? a heteronym - a multi-functional word with different pronunciations.
--
On 04/02/2025 22:46, John Woodgate wrote:
The only things that you can plumb in English are 'the depths'.
?
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Re: In need of some zeners or maybe model them myself
Ivan,
Central Semiconductor has spice models for 3.3V and 11V zener diodes.
You should go to their web site and download the spice models and data sheets.
You will need to evaluate and determine the suitability of the models.
CMPZ5226B.LIB and CMHZ4698.LIB.
Mike
|
Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
Which leads us to plumb the depths of the language issues with a
lead-weighted line, with which we might find a true ground.
(FWIW, I don't believe in "ground" - most nodes labelled "ground"
are actually nets that return current to some reference node.)
Donald.
On 2/4/25 17:45, Tony Casey wrote:
toggle quoted message
Show quoted text
I'm surprised no one has worked with the origins of plumb. Plumbum
is the latin name for lead (hence the chemical symbol Pb). The
English word "Lead" is, of course,? a heteronym - a
multi-functional word with different pronunciations.
--
Regards,
Tony
On 04/02/2025 22:46, John Woodgate
wrote:
The
only things that you can plumb in English are 'the depths'.
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Re: Any Good Reason to Plumb Ground Out of Hier. Schem.
I'm surprised no one has worked with the origins of plumb. Plumbum
is the latin name for lead (hence the chemical symbol Pb). The
English word "Lead" is, of course,? a heteronym - a multi-functional
word with different pronunciations.
--
Regards,
Tony
On 04/02/2025 22:46, John Woodgate
wrote:
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Show quoted text
The
only things that you can plumb in English are 'the depths'.
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No, the way to deal with "errors" at the start of a simulation is to
just ignore them. Simply use the "Time to start saving data" option
in the .TRAN directive. We're talking about specifying the number of
cycles that .FOUR uses when it processes the waveform for harmonic
analysis.
Even when using the "Time to start saving data" technique, you
should not use (at least) the first cycle in a harmonic analysis
because there are always non-uniform samples. I'm not sure why, but
it is easy to see by switching on the "Mark Data Points" option in
the Waveform Viewer.
The solution to the "non-problem" of not simulating long enough is
to always use a calculated analysis time rather than some arbitrary
time. Most .TRAN analyses use a periodic source. Just make the
analysis time an integer multiple of this source's period. For the
life of me, I can't understand why everyone doesn't do this. At
least make the collected data time, i.e. ("Stop time" - "Time to
start saving data") an integer multiple of the period.
As for the .FOUR directive, I've never seen the "number of cycles"
option make any difference at all to the reported THD level unless
there is non-periodic noise in the waveform.
I never really use the .FOUR option for THD measurements, except for
occasional verification, because it can't be used for plotting. I
have made a this a feature request, but so far it hasn't happened.
There a number of other techniques that can be used for these types
of analysis, some of which I have already uploaded. Using a
fundamental notch filter is a pretty simple solution that also
allows for the simple plotting of the distortion residual, which is
visually informative. (This is also how traditional THD meters
worked.) It is also fairly simple to exactly replicate the .FOUR
process by harmonic decomposition using .MEAS:
.meas tran V1re avg -(V(out)-Vavg)*sin(360*time*Freq)
.meas tran V1im avg? (V(out)-Vavg)*cos(360*time*Freq)
.meas tran V1m param hypot(V1re,V1im)
[phase omitted]
.etc...
..to calculate the magnitude of each harmonic. The advantage of this
is that it can then be plotted, using the Right-click > Plot
.step'ed .MEAS Data process once the log file is viewed with Ctrl-L.
.FOUR is probably quicker because it uses compiled code, but it
isn't transparent.
--
Regards,
Tony
On 04/02/2025 18:18, John Woodgate
wrote:
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Using
more cycles gives an average level of each harmonic, which may
compensate for errors due to the 'start' epoch of the simulation.
I find it useful to set the.TRAN simulation to ignore the early
cycles that look distorted, but 'look' is sometimes not good
enough; some transient harmonic levels that are significant are
still being included. If I'm not confident about the reported
result, I change the .TRAN to save results later and/or simulate
for longer. The other aspect of .TRAN simulation time is that if
you set it too short it will not resolve very low frequency
components. For example, a 50ms simulation will not show a 10Hz
component.
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Bell, Dave
eewiz
Tony Casey