Re: Pull-Push transformer for valve amp in LTspice

开云体育

The problem with multiple primaries is that it may create conflictss if two sources are too strongly coupled.
Indeed, when using multiple primaries, one must make sure the voltages, phases and source resistance vs. parasitic resistance are sensible.
I think some transformer sub-circuits don't accept the notion of more than one excitation winding.

Le 21/05/2014 15:54, Vlad imbvlad@... [LTspice] a écrit?:

Show quoted text

?

> Indeed a dual primary xfmr can be created in LTspice.

Well, I just tried it and you're right, it does work, but I know there was a discussion some time ago (years, probably) about not being able to make a more than one primary transformer in LTspice. Maybe with the Chan core? I really can't remember now.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Reference Information

#72649

I'll add another vote. I've used LT Spice daily for many years now... ?The book is excellent even for people reasonably skilled in the art. The sections dealing with magnetics simulations are particularly good. There is a lot here YOU don't know yet. LOL

Re: Pull-Push transformer for valve amp in LTspice

#72648

> To my great shame I must admit I haven't been able to edit the OT values in the Fender schemo.

Using the "Fender Twin Reverb" example, the output transformer is modeled in the model file "transPPb.INC". Any text editor should do. I also see extra nodes/elements for parasitic resistances & co. instead of using the builtin Rser/Rpar/etc, but maybe it's intentional, for the purpose of showing.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Pull-Push transformer for valve amp in LTspice

#72647

> Indeed a dual primary xfmr can be created in LTspice.

Well, I just tried it and you're right, it does work, but I know there was a discussion some time ago (years, probably) about not being able to make a more than one primary transformer in LTspice. Maybe with the Chan core? I really can't remember now.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Pull-Push transformer for valve amp in LTspice

#72646

开云体育

In fact all these examples use a sub-circuit instead of coupled inductors, but I know that coupled inductors work and are IMO easier to edit.
To my great shame I must admit I haven't been able to edit the OT values in the Fender schemo.

Le 21/05/2014 15:41, Jerry Lee Marcel jerryleemarcel@... [LTspice] a écrit?:

Show quoted text

?

Indeed a dual primary xfmr can be created in LTspice.
You need to include all windings in the K statement.

There is a beautiful example of tube amp in the Files, in fact more than one:
Fender Twin Reverb AB763 and Fender Twin Reverb AA270

Also Fisher500c and Laney_Marshall_EL34_50Watt

Le 21/05/2014 15:32, Vlad imbvlad@... [LTspice] a écrit?:

?

I don't know if it's possible to simulate a double-primary transformer in LTspice. At least not with inductors and coupling between them. Still, if others have different answers, it would be useful to follow the steps in the group's home page about asking for help, how to upload schematics and where.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Pull-Push transformer for valve amp in LTspice

#72645

开云体育

Indeed a dual primary xfmr can be created in LTspice.
You need to include all windings in the K statement.

There is a beautiful example of tube amp in the Files, in fact more than one:
Fender Twin Reverb AB763 and Fender Twin Reverb AA270

Also Fisher500c and Laney_Marshall_EL34_50Watt

Le 21/05/2014 15:32, Vlad imbvlad@... [LTspice] a écrit?:

Show quoted text

?

I don't know if it's possible to simulate a double-primary transformer in LTspice. At least not with inductors and coupling between them. Still, if others have different answers, it would be useful to follow the steps in the group's home page about asking for help, how to upload schematics and where.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Pull-Push transformer for valve amp in LTspice

#72644

I don't know if it's possible to simulate a double-primary transformer in LTspice. At least not with inductors and coupling between them. Still, if others have different answers, it would be useful to follow the steps in the group's home page about asking for help, how to upload schematics and where.

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Pull-Push transformer for valve amp in LTspice

#72643

I am having trouble modelling an ideal Pull-Push center tap 8 ohms transformer with a 6.7k primary anode-anode impedance in LTspice.?

Formula:?

8*(Np/Ns)^2=7.6k
Thus, Np/Ns=30.82/1

Here are my LTspice schematic. It doesn't give the correct results. Could someone please help me out?

Re: Regarding LT1521-5

John Woodgate

#72642

In message <F95E7D51-CF12-459A-9C1E-8E9BFD35813C@...>, dated
Wed, 21 May 2014, "Mark Gurries gurriesm@... [LTspice]"
<LTspice@...> writes:

I explained this to him on March 26th when he asked the same exact
question. ?Kumar does not seem to learn.I suspect that Kumar is from a society that believes that you do not
always get the same answer to a question. Experience does indeed
indicate some truth in that, for some types of question, but not all.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Re: Regarding LT1521-5

#72641

I explained this to him on March 26th when he asked the same exact question. ?Kumar does not seem to learn.

As a Linear Tech internal Senior Applications engineer located at the factory for 14 years who trained FSE/FAE, a schematic would never be allowed to leave the company. ? As a regular conduct of business, ?even applications engineers never saw a schematic too. ? Not that they could not see it. ?It just that in most cases unless there was some difficult debug involved during IC development, there was never any need to. ? Internal application engineers could simply talk to the IC designer on the phone at any time and get all the info they needed. ? FAE's would have even a harder time getting any such information since they are not really allowed to talk to the IC designers for common customer support issues. ?The are supposed to go to the internal applications people first for support. ?The goal it to keep the IC designer designing IC's and not get caught up in everyday support issues.

Linear does not allow its IC to go into any medical product that involves life support. ?It is a liability issue Linear does not want to accept. ?If there is medical application involved, John is correct that discussing it with a sales engineer would be advisable to see if Linear will allow it.

On May 21, 2014, at 1:15 AM, John Woodgate jmw@... [LTspice] wrote:

?
In message <1400658314.45008.YahooMailNeo@...>,
dated Wed, 21 May 2014, "Kesi Kumar kesikumar.iitg@... [LTspice]"
<LTspice@...> writes:

>i want discrete circuit dirgram of LT1521-5 , i have block digram of
>LT1521-5 but i dont want block digram as i m working on implant device
>so i cannot block diagram so, can anybody suggest me from where should
>i get whole circuit digram of LT1521-5. I had seen
>http://www.linear.com/product/LT1521? details ...but actually i want
>searching for discrete diagram ....can anybody give me right path to
>proceed..

The information you require is almost certainly confidential. You should
explain your requirements to your Field Service Engineer or other formal
contact at LT. In any case, you need to discuss the use of ANY
electronic device in an implanted device with the manufacturer.
--
OOO - Own Opinions Only. With best wishes. See
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Best Regards,

Mark Gurries

Electrical Engineer

DCC Website & NMRA DCC Clinics:

Re: Regarding LT1521-5

John Woodgate

#72640

In message <1400658314.45008.YahooMailNeo@...>,
dated Wed, 21 May 2014, "Kesi Kumar kesikumar.iitg@... [LTspice]"
<LTspice@...> writes:

i want discrete circuit dirgram of LT1521-5 , i have block digram of
LT1521-5 but i dont want block digram as i m working on implant device
so i cannot block diagram so, can anybody suggest me from where should
i get whole circuit digram of LT1521-5. I had seen
 details ...but actually i want
searching for discrete diagram ....can anybody give me right path to
proceed..The information you require is almost certainly confidential. You should
explain your requirements to your Field Service Engineer or other formal
contact at LT. In any case, you need to discuss the use of ANY
electronic device in an implanted device with the manufacturer.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Regarding LT1521-5

#72639

i want discrete circuit dirgram of LT1521-5 , i have block digram of LT1521-5 but i dont want block digram as i m working on implant device so i cannot block diagram so, can anybody suggest me from where should i get whole circuit digram of LT1521-5. I had seen ? details ...but actually i want searching for discrete diagram ....can anybody give me right path to proceed..

Thank You

Kesi Kumar

?

Re: Current Step Algorithm

#72638

> It is maybe faster to not use compares but formulate all as
> float-operations: mul, div.

That's not entirely true: multiplications and divisions are much slower compared to conditional checks, which may be the fastest, computational-wise. Still, I'll stick to what I said related to not using behavioural sources but, instead, E or G sources within a subcircuit. As they say, "your mileage may vary".

Vlad
______________________
-- holding, among others:
a universal analog/digital filter, block-level models
for power electronics (and not only), math blocks
with a more stream-lined approach, some digital
ADC, DAC, (synchronous-)counter, JKflop, etc.

Re: Best LM3x7 model?

#72637

Hello,

I want just remember hat models from different vendors are in our section Files.

Files > Lib > Linear Regulators
Files > Lb > LM317

I haven't checked which is best regarding phase and frequency response.

Best regards,
Helmut

Best LM3x7 model?

#72636

Hello all. What is the best model for these chip regulators? I would like a model that accurately shows the phase behavior of PSRR and output impedance, if possible. Otherwise I will probably try to make my own model, but I would prefer not to reinvent the wheel.

Thanks.

Re: Photodiode

#72635

Hello,

A photo diode is simply a large area diode. The large area results in large capacitance Cjo. The incident light will be converted to current in the photo diode. Thus the second part of the model is simply a current source with current proportional to the amount of received light. This current source is parallel to this diode.

The file "all_files.htm" with links to every file is here:

Search in all_files.htm with "photo" and open/run the examples you will find.

The do a second search with "solar".

Best regards,
Helmut

Re: Analog Switch model with charge injection?

#72634

Hello,

The most simple solution will be one or two capacitors. One between the control voltage and the switch-input and the other between the control voltage and the switch-output. You can add some voltage dependence if you use a diode(Cjo) in reverse operation instead of a fixed capacitance.

Best regards,
Helmut

Re: Current Step Algorithm

ehydra

#72633

Hi JH -

Sorry, I can't help you because it looks to complicated what you have done.
Maybe it helps if you post the whole circuit. Even then the result thru help is not a whole faster reconfiguration but with new parameter settings. tripdt etc.

It is maybe faster to not use compares but formulate all as
float-operations: mul, div.

max/min is not in the help-file because the whole counter circuit is a hack and surely not very liked by Mike.

- H.

tindelsurf@... [LTspice] schrieb:

Show quoted text

Henry,
I was able to figure it out with your help... and got my simulation
time down to ~4.25 minutes, a great improvement... but now I at least
know that the count table isn't what is slowing me down
significantly.  I just have a complex loop.  And as Helmut pointed
out... I knew the DFF solution wasn't very stable.
One final question: is there a good way to speed up the transitions
of the Sample and Holds?  I tried using td/trise/tfall, but it didn't
appear to effect anything.
Thanks for giving me the hint on the max/min counts too... that
helped a lot!  I couldn't find anything in the help files about that!
Love this place - you guys always get me pointed the right direction.
Just FYI - if anyone ever reads this again (the yahoo search sucks,
so I doubt it)... I was able to make Henry's suggestion a window
comparator by setting Vdir to be centered about 0 and making the
following statement for B1:
V=if(V(dir)<-0.05,-1,if(V(dir)>0.05,1,0)).  I also speed up the clock
to 1k to get my 1ms count increments.

Analog Switch model with charge injection?

[email protected]

#72632

I am looking for a model of, for example, a DG201 analog switch, that models the actual MOSFETS used in the switch. ?I would like the simulation to show the charge injection that takes place during switching. ?Any other analog switch of this generation would be fine, too. ?I know that Analog Devices has models that use "switch" elements, but I am looking for something that is a little more real. ?Does anyone know about these parts? Would someone know ?of a MOSFET model that is good for this generation??

Thanks in advance

?

Re: Current Step Algorithm

#72631

Henry,

I was able to figure it out with your help... and got my simulation time down to ~4.25 minutes, a great improvement... but now I at least know that the count table isn't what is slowing me down significantly.? I just have a complex loop.? And as Helmut pointed out... I knew the DFF solution wasn't very stable.

One final question: is there a good way to speed up the transitions of the Sample and Holds?? I tried using td/trise/tfall, but it didn't appear to effect anything.

Thanks for giving me the hint on the max/min counts too... that helped a lot!? I couldn't find anything in the help files about that!

Love this place - you guys always get me pointed the right direction.

Just FYI - if anyone ever reads this again (the yahoo search sucks, so I doubt it)... I was able to make Henry's suggestion a window comparator by setting Vdir to be centered about 0 and making the following statement for B1: V=if(V(dir)<-0.05,-1,if(V(dir)>0.05,1,0)).? I also speed up the clock to 1k to get my 1ms count increments.

JH