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--- In LTspice@..., "yogasmitha" <amba_200@...> wrote:

Hello Rick,
Thanks, But i have connected the ground on the R285 to R295 resistors. Which is ground. Do you think there has to be some big resistor at the return path? say 100K since the input and the output side will have a common grounds and as i said it will short the return path?

Do you have any other source or database which can give me the esr of the caps i am using.
SInce i know these will contribute a lot to the instability.

another thing i want to know is " i have used the inductor as a flyback transf and want to know if the series resistance is calculated by the ltspice tool on its own"
i have given the direct values of 0.045Ohm what is given in the datasheet. What actually is seen by the coil is based on the connectivity. i.e parallel or series etc.., Will lt tool calculate on own since the coil craft vendor told me the LT tool will do. I just wanted to clarify once with you.

What are the other values/components which affect the stability of the flyback?
Should i try to do something with the comp pin(values) of the LT1241 device?

Ple Help.
Thanks,
Yoga

Yoga,

You're right, you do have a connection there. When I looked at your circuit before, I saw a very large voltage between ground and the common bus on the bottom half of the circuit. This caused by the inductance between ground and the common bus and the very larges start up currents in the circuit. I removed UIC from the .TRAN command and the startup currents were greatly reduced. (You could do this other ways, but this was easy to do.) You should revisit your filtering scheme.

After I removed UIC, the circuit seemed to behave OK. Specifically, what do you think is wrong?

LTspice contains a library of caps with their ESRs. In addition, part manufactures specify ESR.

LTspice does not compute the inductor series resistance but it defaults to .001 ohms for inductors that are not mutually coupled to others. LTspice also has a library of inductors, and vendors specify performance. The model LTspice uses for an inductor is given in the help file.

Rick

I am assuming he does not have multiple yahoo e-mail names

At this point I think he does.

I think the main problem is that in a subcircuit, the connecting lines and layout of an equivalent schematic are basically missing.

So only way I know of is to go through the subcircuit line by line, and laboriously create the schematic drawing of that in LTspice schematic editor 'by hand'. The nodes (connecting lines) will have numbers in the subckt which can also be named the same on the drawing which does help.

Unless anyone knows differently :D

Am I being too simplistic or does this just mean that the e-mail has to be someone @ yahoo.com ? Did not know about the gmail option, but may not be as reliable. (?)

I am assuming he does not have multiple yahoo e-mail names

--- In LTspice@..., David Hawkins <dwh@...> wrote:

Hi Tony,

You cannot save an array of measurements, unfortunately, so you will
need a .meas statement for each frequency of each parameter you want
to save. If there are a lot, it might be better to put all the .meas
statements into an .included file to save cluttering up your
schematic.

I'm not sure if that is totally true - depending on what you define
as 'an array of measurements' :)

You can use a .step statement and then extract the step details from
the .raw file. I wrote examples for .tran and .ac analysis here:



I mention this in case its a method you have not tried before.

Cheers,
Dave

Hello Dave,

Thanks for the Matlab example - I'll get around to trying that sometime. I assume it will work after a fashion in Octave, as Matlab is beyond my budget.

Unfortunately, it won't be much use in this case because although you can coerce LTspice into using a .step param Freq construct in .AC, the Freq array doesn't seem to be available for .meas postprocessing. I tried it and Freq always just returns the last value in the range.

The method I proposed does work, although you do need a "find" in the .meas statement, as Helmut pointed out. You don't get an array that you can plot, just a list of separate measurements at various frequencies. My interest in doing this is generally to extract the S parameters, but the resulting logfile data doesn't look much like Touchstone? SnP format, so a fair amount of knife and forking is required to reformat the data. But if all this was too easy, anyone could do it!

Regards,
Tony

A friend of mine, next to me, said: "He must be different", but what he means by that is "He's not normal" :) , but in a good way. I, for one, can only be glad he is so.

Vlad

It sounds great, I am so thankfull for all of these information. These are all about what I am looking for, wish help some others too.
Thanks again dear professionals.

--- In LTspice@..., "Gandolf" <charlesknouse27@...> wrote:

After searching LTspice files exhaustively for LED models, it seemed to me that the best ones were Helmut's, i.e. this one for a GaAs LED:

*Typ RED GaAs LED: Vf=1.7V Vr=4V If=40mA trr=3uS
.MODEL Red_Led_660nm3mm D (IS=93.2P RS=42M N=3.73 BV=4 IBV=10U
+ CJO=2.97P VJ=.75 M=.333 TT=4.32U)

The LED I wish to model is the WP710A10SRC/E from Kingbright (3mm GaAs 660 nm); there are some small but (because I'm stringing a lot of 'em ;) important differences from the model above...

....namely, 1.85 typical Vf at If=20 mA typical, 30 mA max, 45 pF capacitance, 10 uA reverse current (and unfortunately, that's it from the datasheet!!).

Would someone please explain what all the parameters are between the parentheses in Helmut's model above and how I change them to better simulate the Kingbright LED? I searched for LED spice parameter's, but could not come up with any info on what IS, RS, N, BV, etc, stand for.

Very Best, Maturin

Hello Maturin,

An LED is just a diode, as you get glean from the .model line you quote above. I don't know where you searched for the model parameters, but they are all listed in the LTspice Helpfile under "diode", and elsewhere - for example, the PSpice manual.

The most convenient way to generate a diode model is the use Henrick Jan Zwerver's Diodemodeller software located in the file area:



You can then tweak the parameters within LTspice, if desired, when plotting the characteristics in a device jig.

Regards,
Tony

.model 1N746 D(Is=10p Rs=13.65 N=1.27 Tt=50n Cjo=582.6p VJ=0.75 M=0.33
Bv=3.027 IBV=0.01 Vpk=3.3 Iave=200m diss=500m mfg=Motorola type=zener)

.model 1N4153 D(Is=0.1p Rs=6 Tt=3n Cjo=1p Bv=100 Ibv=0.1p Vpk=100 Iave=200m
diss=500m mfg=National type=silicon)




Suusi M-B

--- In LTspice@..., "Shadow" <shadowvpr123@...> wrote:

Good day to all...

Do any of you guys have 1n4153 and 1n746a models for ltspice... I need to simulate a circuit using those 2 diode...

Any models? or similar diode models? Thanks..

.MODEL 1N4153 D(Is=0.1p Rs=6 CJO=1p Tt=3n Bv=100 Ibv=0.1p)

Hello Rick,
Thanks, But i have connected the ground on the R285 to R295 resistors. Which is ground. Do you think there has to be some big resistor at the return path? say 100K since the input and the output side will have a common grounds and as i said it will short the return path?

Do you have any other source or database which can give me the esr of the caps i am using.
SInce i know these will contribute a lot to the instability.

another thing i want to know is " i have used the inductor as a flyback transf and want to know if the series resistance is calculated by the ltspice tool on its own"
i have given the direct values of 0.045Ohm what is given in the datasheet. What actually is seen by the coil is based on the connectivity. i.e parallel or series etc.., Will lt tool calculate on own since the coil craft vendor told me the LT tool will do. I just wanted to clarify once with you.

What are the other values/components which affect the stability of the flyback?
Should i try to do something with the comp pin(values) of the LT1241 device?

Ple Help.
Thanks,
Yoga

After searching LTspice files exhaustively for LED models, it seemed to me that the best ones were Helmut's, i.e. this one for a GaAs LED:

*Typ RED GaAs LED: Vf=1.7V Vr=4V If=40mA trr=3uS
.MODEL Red_Led_660nm3mm D (IS=93.2P RS=42M N=3.73 BV=4 IBV=10U
+ CJO=2.97P VJ=.75 M=.333 TT=4.32U)

The LED I wish to model is the WP710A10SRC/E from Kingbright (3mm GaAs 660 nm); there are some small but (because I'm stringing a lot of 'em ;) important differences from the model above...

....namely, 1.85 typical Vf at If=20 mA typical, 30 mA max, 45 pF capacitance, 10 uA reverse current (and unfortunately, that's it from the datasheet!!).

Would someone please explain what all the parameters are between the parentheses in Helmut's model above and how I change them to better simulate the Kingbright LED? I searched for LED spice parameter's, but could not come up with any info on what IS, RS, N, BV, etc, stand for.

Very Best, Maturin

Thank you very much Helmut. I can handle all of that myself. I am just studying OP-Amps also and need this one for a color organ circuit that I need ?figured out. Best Kevin.


________________________________
From: Helmut <helmutsennewald@...>
To: LTspice@...
Sent: Thursday, August 30, 2012 5:44 PM
Subject: [LTspice] Re: LF353 Pspice MACROMODEL


?


--- In LTspice@..., "kbyrne10" <kbyrne10@...> wrote:

I down loaded a OP-AMP I need to study like your TL072 verses LT1057
Folder. Question What do I have to do in PSpad and or on schematic to use the Universal Symbol "opamp2.
It states: * LF353 OPERATIONAL AMPLIFIER "MACROMODEL" SUBCIRCUIT
.SUBCKT LF353 1 2 3 4 5
Is this just a .include LF353 .SUBCKT LTspice directive on schematic.
or do I have to open a window & change parameters again and if so what should it read for a OP-Amp instead of a Zener Diode. I just need the info to store in my collection of files for all types of parts introduced into LTspice so in the future I have help all figured out
if it is not a problem in a little bit of a guide not a drawn out affair. Best wishes Kevin

Hello Kevin,

You can use the symbol opamp2, because it has the same pin-order
+in -in V+ V- out.
You will need then only an additional .include LF353.mod in
the schematic.
The value have to be LF353/NS, because it's the name in the
.subckt line.

You can look-up an example.

Files > Lib > LF353_LF412_test.zip

Best regards,
Helmut

* connections: non-inverting input
* | inverting input
* | | positive power supply
* | | | negative power supply
* | | | | output
* | | | | |
* | | | | |
.SUBCKT LF353/NS 1 2 99 50 28




[Non-text portions of this message have been removed]

Thank you Helmut... :D

--- In LTspice@..., "kbyrne10" <kbyrne10@...> wrote:

I down loaded a OP-AMP I need to study like your TL072 verses LT1057
Folder. Question What do I have to do in PSpad and or on schematic to use the Universal Symbol "opamp2.
It states: * LF353 OPERATIONAL AMPLIFIER "MACROMODEL" SUBCIRCUIT
.SUBCKT LF353 1 2 3 4 5
Is this just a .include LF353 .SUBCKT LTspice directive on schematic.
or do I have to open a window & change parameters again and if so what should it read for a OP-Amp instead of a Zener Diode. I just need the info to store in my collection of files for all types of parts introduced into LTspice so in the future I have help all figured out
if it is not a problem in a little bit of a guide not a drawn out affair. Best wishes Kevin

Hello Kevin,

You can use the symbol opamp2, because it has the same pin-order
+in -in V+ V- out.
You will need then only an additional .include LF353.mod in
the schematic.
The value have to be LF353/NS, because it's the name in the
.subckt line.

You can look-up an example.

Files > Lib > LF353_LF412_test.zip

Best regards,
Helmut


* connections: non-inverting input
* | inverting input
* | | positive power supply
* | | | negative power supply
* | | | | output
* | | | | |
* | | | | |
.SUBCKT LF353/NS 1 2 99 50 28

I down loaded a OP-AMP I need to study like your TL072 verses LT1057
Folder. Question What do I have to do in PSpad and or on schematic to use the Universal Symbol "opamp2.
It states: * LF353 OPERATIONAL AMPLIFIER "MACROMODEL" SUBCIRCUIT
.SUBCKT LF353 1 2 3 4 5
Is this just a .include LF353 .SUBCKT LTspice directive on schematic.
or do I have to open a window & change parameters again and if so what should it read for a OP-Amp instead of a Zener Diode. I just need the info to store in my collection of files for all types of parts introduced into LTspice so in the future I have help all figured out
if it is not a problem in a little bit of a guide not a drawn out affair. Best wishes Kevin

--- In LTspice@..., "imbvlad" <imbvlad@...> wrote:

Mike,

The -nowine switch is documented in the LTspice's help manual, see Modes of Operation > Command Line Switches:

"Prevent use of WINE(Linux) workarounds."

[...]

Good luck understanding,
Vlad :)

Thanks Vlad. That was a very good explanation. I'm running Ubuntu 10.04.02 LTS, but I never had any display problems or found a need to use the command line switches.

Most of the time I run LTspice in VirtualBox in WinXP SP3, and once in a while the cursor gets screwed up and blinks furiously. I simply press Esc and that stops it. I haven't found any other problems.

I believe LTspice is by far the most reliable code I have ever seen for XP or Ubuntu. I don't know how Mike can be such an expert in so many different fields - SPICE, Windows programming, electronics, and convincing the management at Linear to let him create the best SPICE program on the planet. It's just amazing.

Thanks,

Mike

--- In LTspice@..., "Tony Casey" <tony@...> wrote:

--- In LTspice@..., "Majid" <rafei.majid@> wrote:

Dear Helmut,
Do you know what is the correct syntax of network parameters for measuring purposes? (Z(11) or Z11 or ...?), Thanks.

Hello Majid,

The syntax is exactly the same as you would use in the waveform window, so I would develop the .meas statements in conjunction with plots of the data you're interested in, even if in the end you want to only use the command line (batch mode).

So, for example, if you're plotting Z11(V1) (assuming V1 is the source you're using), you would add the statements like:

.meas AC Z11-200M Z11(V1) at 200Meg; Z11 at 200MHz
.meas AC Z11-300M Z11(V1) at 300Meg; Z11 at 300MHz

...etc

You cannot save an array of measurements, unfortunately, so you will need a .meas statement for each frequency of each parameter you want to save. If there are a lot, it might be better to put all the .meas statements into an .included file to save cluttering up your schematic.

You can find all the information on syntax, surprisingly enough, in the Helpfile.

Regards,
Tony

Hello Tony,

Thanks for your explanation. I thought to complicated when I
advised to open the raw-file. Just looking in the "Add trace"
dialog as you have advised is a lot more convenient.

Best regards,
Helmut

Hi Tony,

You cannot save an array of measurements, unfortunately, so you will
need a .meas statement for each frequency of each parameter you want
to save. If there are a lot, it might be better to put all the .meas
statements into an .included file to save cluttering up your
schematic.

I'm not sure if that is totally true - depending on what you define
as 'an array of measurements' :)

You can use a .step statement and then extract the step details from
the .raw file. I wrote examples for .tran and .ac analysis here:



I mention this in case its a method you have not tried before.

Cheers,
Dave

--- In LTspice@..., "Majid" <rafei.majid@...> wrote:

Dear Helmut,
Do you know what is the correct syntax of network parameters for measuring purposes? (Z(11) or Z11 or ...?), Thanks.

Hello Majid,

The syntax is exactly the same as you would use in the waveform window, so I would develop the .meas statements in conjunction with plots of the data you're interested in, even if in the end you want to only use the command line (batch mode).

So, for example, if you're plotting Z11(V1) (assuming V1 is the source you're using), you would add the statements like:

.meas AC Z11-200M Z11(V1) at 200Meg; Z11 at 200MHz
.meas AC Z11-300M Z11(V1) at 300Meg; Z11 at 300MHz

...etc

You cannot save an array of measurements, unfortunately, so you will need a .meas statement for each frequency of each parameter you want to save. If there are a lot, it might be better to put all the .meas statements into an .included file to save cluttering up your schematic.

You can find all the information on syntax, surprisingly enough, in the Helpfile.

Regards,
Tony