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--- In LTspice@..., Tan Micheline Tambayong <micheline.tambayong@...> wrote:

I already uploaded the file under name Pefficiency_analysis.asc.

Methode how to calculate efficiency is missing.

Please notice that R1 is not connected to gnd. I suppose you calculated like this: voltage should be: V(n003)-V(n004). Current is I(R1) so power is (V(n003)-V(n004))*I(R1)
Divide Output power by input power?...

Your uploaded simulation works for me.

hws

Hi Micheline,

Could you please post the circuit schematics, Symbols, and models and all relevant files in the Temp files of this group ? It is a lot easier with a schematic to troubleshoot.

Best regards,

Michael




To: LTspice@...
From: micheline.tambayong@...
Date: Mon, 19 Sep 2011 15:21:03 +1000
Subject: [LTspice] SPICE Error






Does anyone know what its means when LTspice give error:
"Singular matrix: check node n002
Iteration No. 1"

The circuit is made by AC voltage source, resistor (series with the voltage
source), bridge rectifier, capacitor, resistor paralleled with the capacitor
as a load at the output, and ground. The circuit is plotting and simulating
just fine for small value of capacitor. But when I increase the capacitor
value above 16uF, LTspice give the above error. But for some capacitor
values (eg. 20uF) it's fine again, and when I increase it again (eg.21uF),
it gives error again. So LTspice gives error for most of capacitor value
above 16uF but not all.. Also, for some value, it simulating but then the
plot stops in the middle. The value of the capacitor that gives an ok plot
and error are randoms (no pattern). So does anyone know, what's the reason
that the LTspice behaves like this?

Thanks in advance..

Kind regards,
Micheline

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






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

--- In LTspice@..., "Charly Engineering" <charly020664@...> wrote:

very kindly people here by
...
much more than in our german newsgroups :-)

Which german newsgrop?

hws

Hi Helmut,
Thanks for the reply. I already uploaded the file under name
Pefficiency_analysis.asc.
Please try to simulate the power in V1 and power in R1 since I am analyzing
the Power efficiency (Pout/Pin) of the circuit. Also if you try to simulate
using C = 16uF it's simulating just fine but it gives error when you try C =
17uF... You can try other value of C as well. It gives error for only some
values of C above 16uF.
Hope you can find out why it behaves as such..
Thanks so much for the help

Kind regards,
Micheline

--- In LTspice@..., "gasoltroll" <johan.lans@...> wrote:

Hi
i'm looking at an impedance curve of a non-ideal tantalum capacitor in LTSpice. The test circuit and impedance curve is seen in this screengrab:

The spice file is here .
So, the imdpedance curve shows the expected impedance minimum, but also an unexpected maximum at about 100MHz, where there is also a polarity switch in phase. This feature does not show up if I do an impedance plot in octave:


octave:1> f = [1000:1000:1e9];
octave:2> C = 2e-3C = 0.0020000
octave:3> R = 2e-3R = 0.0020000
octave:4> L = 1e-9L = 1.0000e-09
octave:5> z = R + f.*2*pi*j*L-1./(f.*2*pi*j*C)
octave:6> loglog(f,abs(z))
octave:7> semilogx(f,atand(imag(z)./real(z)))

Which result in these plots



The parameters in the octave code are the same as in LTSpice component. Anyone know where this comes from? The phases look pretty different, is there something wrong with the test circuit?

Hello Johann,

Please set a value for Cpar when you have set Lser.

Right-mouse-click on the capacitor. Then set the following.

Equivalent parallel capacitance(Cpar): 0p

Best regards,
Helmut

--- In LTspice@..., Tan Micheline Tambayong <micheline.tambayong@...> wrote:

Does anyone know what its means when LTspice give error:
"Singular matrix: check node n002
Iteration No. 1"

The circuit is made by AC voltage source, resistor (series with the voltage
source), bridge rectifier, capacitor, resistor paralleled with the capacitor
as a load at the output, and ground. The circuit is plotting and simulating
just fine for small value of capacitor. But when I increase the capacitor
value above 16uF, LTspice give the above error. But for some capacitor
values (eg. 20uF) it's fine again, and when I increase it again (eg.21uF),
it gives error again. So LTspice gives error for most of capacitor value
above 16uF but not all.. Also, for some value, it simulating but then the
plot stops in the middle. The value of the capacitor that gives an ok plot
and error are randoms (no pattern). So does anyone know, what's the reason
that the LTspice behaves like this?

Thanks in advance..

Kind regards,
Micheline

Hello Micheline,

This error message simply means that LTspice couldn't solve
the matrix. Maybe your circuit has an open nets.

Please upload your circuit to this group for a test to the
following location.

Files > Temp > yourcircuit.asc



Best regards,
Helmut

SPICE (and LTspice is no exception) can have additional shunt elements
from every node to ground, added to help convergence. ?I've kind of
lost track of exact details, over the years, but there can be a gshunt
(conductance) and a cshunt (capacitance) added to every node.

I think cshunt is resonating with the tantalum's inductance.

I don't know exactly where the value of this capacitance is set (other
than an .OPTIONS statement), but I saw in the "Hacks" tab of the
Control Panel, there is a setting for "Minimum shunt to main
capacitance ratio". ?Changing that number moves the parallel
resonance,?so I think it is the cause. ?If you make the "Hacks" value
very small, or zero, the curve looks like your Octave plot.
Andy

Does anyone know what its means when LTspice give error:
"Singular matrix: check node n002
Iteration No. 1"

The circuit is made by AC voltage source, resistor (series with the voltage
source), bridge rectifier, capacitor, resistor paralleled with the capacitor
as a load at the output, and ground. The circuit is plotting and simulating
just fine for small value of capacitor. But when I increase the capacitor
value above 16uF, LTspice give the above error. But for some capacitor
values (eg. 20uF) it's fine again, and when I increase it again (eg.21uF),
it gives error again. So LTspice gives error for most of capacitor value
above 16uF but not all.. Also, for some value, it simulating but then the
plot stops in the middle. The value of the capacitor that gives an ok plot
and error are randoms (no pattern). So does anyone know, what's the reason
that the LTspice behaves like this?

Thanks in advance..

Kind regards,
Micheline

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

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

The "Pick New Transistor" function is wonderful, allowing me to sort by key features for an easy selection of the available library of parts. Is there any way to access a selector menu like this for the wide selection of LT opamps? I really want to use LT opamps in my current design, but I'm getting tired of going up to the LT site and using their feature selection tool to find an appropriate opamp. If I think I need an amplifier with a faster slew rate to solve my immediate problem, it would be nice to get into the LTspice opamp selection menu, sort by slew rate, then select a device that has the proper range of features. I often find myself running simulations in places where I don't have access to the LT website, so this feature would be really nice to have. Is it already there and I just don't know about it?

Hello Carl,

I'm not sure whether this would rate as equivalent to the "Pick New Transistor" dialogue, but if you open the parts chooser and browse to the Opamps sub-section, you will find pretty much all of LT's opamps there. If you step through the list, most of them have a potted description of what they are and what they do, alongside the preview of the symbol.

Would this do for you, or were you thinking of something else?

Regards,
Tony

Maybe I'm just a little bit lazy, since there are over 300 amplifiers to chose from in the LT selection window. Yes, they do have a one-line overview of the good specs, but being able to sort (like on the website selector page) is what I was hoping for.
Thanks to those who had other suggestions (universal opamp), but I wanted to "play with real opamps" before I ordered some samples for my breadboard.

really,

very kindly people here by

...

much more than in our german newsgroups :-)

regards, Leo ...

I used to get strange differences between linear and log scales in earlier
version of LTspice, though I haven't had any in the last year or two. They
were never explained, but they certainly disappeared.

If it's not an early version, have a look at the no of points per octave you
are using. If you have too few there can be some very strange plotting as
the otherwise seemingly excellent interpolation does its best with the
derivatives it's given. A bouncing ball shape is one definite symptom of
this.

CT

On 18 September 2011 20:15, gasoltroll <johan.lans@...> wrote:

**


Hi
i'm looking at an impedance curve of a non-ideal tantalum capacitor in
LTSpice. The test circuit and impedance curve is seen in this screengrab:

The spice file is here .
So, the imdpedance curve shows the expected impedance minimum, but also an
unexpected maximum at about 100MHz, where there is also a polarity switch in
phase. This feature does not show up if I do an impedance plot in octave:

octave:1> f = [1000:1000:1e9];
octave:2> C = 2e-3C = 0.0020000
octave:3> R = 2e-3R = 0.0020000
octave:4> L = 1e-9L = 1.0000e-09
octave:5> z = R + f.*2*pi*j*L-1./(f.*2*pi*j*C)
octave:6> loglog(f,abs(z))
octave:7> semilogx(f,atand(imag(z)./real(z)))

Which result in these plots



The parameters in the octave code are the same as in LTSpice component.
Anyone know where this comes from? The phases look pretty different, is
there something wrong with the test circuit?

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

It works, thank You Suusi for the lib-extension ....

have all a nice new week ...

best regards, Leo ...

--- In LTspice@..., "Suusi M-B" <smalcolmbrown@...> wrote:

Oops Sorry

Found the problem and fixed it

It turns out that I managed to miss the p from the grid plate capacitance so it went from 1.6pf to 1.6 farads hence the weird results

I do wish the LTspice's editor didn?€?t default to overtype every time you paste into a document



Suusi Malcolm-Brown

great Suusi :-), best regards, Leo

Oops Sorry

Found the problem and fixed it

It turns out that I managed to miss the p from the grid plate capacitance so it went from 1.6pf to 1.6 farads hence the weird results

I do wish the LTspice's editor didn¡¯t default to overtype every time you paste into a document



Suusi Malcolm-Brown

They are clearly very different types of model; the EC/PC86 uses a
B-source while the EC81 uses parameters. The transient simulation
failure shows that the EC81 model doesn't work, but I don't know why. I
don't see any error in it, but I might not recognise one if it bit me.
I'm just wondering if LTspice understands those parameters without some
extra information.

The extra informations for the EC81 are in the .subckt TRIODE in the Koren_Tubes.cir.

I think they use subcircuits from subcircuits :-)...

best regards, Leo

In message <j55l56+a39e@...>, dated Sun, 18 Sep 2011, Charly
Engineering <charly020664@...> writes:

--- In LTspice@..., John Woodgate <jmw@...> wrote:

In message <j55k6t+5cer@...>, dated Sun, 18 Sep 2011, Charly
Engineering <charly020664@...> writes:

Maybe the models differ in some vital respect. Please upload your EC86
.asc and model.
--

uploaded, thanks, Leo ...

They are clearly very different types of model; the EC/PC86 uses a
B-source while the EC81 uses parameters. The transient simulation
failure shows that the EC81 model doesn't work, but I don't know why. I
don't see any error in it, but I might not recognise one if it bit me.
I'm just wondering if LTspice understands those parameters without some
extra information.

The result is even more bizarre if you delete the 50 ¦ÌF!
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

--- In LTspice@..., John Woodgate <jmw@...> wrote:

In message <j55k6t+5cer@...>, dated Sun, 18 Sep 2011, Charly
Engineering <charly020664@...> writes:

Maybe the models differ in some vital respect. Please upload your EC86
.asc and model.
--

uploaded, thanks, Leo ...

In message <j55k6t+5cer@...>, dated Sun, 18 Sep 2011, Charly Engineering <charly020664@...> writes:

I don't understand why the EC86-transient-analyse is succesful and the EC81 with the Koren_Tube-model in nearly the same circuit not.

Maybe the models differ in some vital respect. Please upload your EC86 .asc and model.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

It would help if you told us what you are trying to make a simulation
of.
--

Yes, I work at noise-matched active antennas. The Rser and Cser of the voltage-source simulate a electrical short antenna at about 1 MHz.

I would not try to use a tube, but unfortunately I need big signal solidity up to fields of 20 V/m or 30 V/m for usage near a big transmitter.

I try to aspire a bandwidth from 10 kHz to min. 30 Mhz. 10 kHz is not simple with a tube.

I first tried with an EC86, that works, but an EC81 is much more better like my databook told me.

It is the first time, I used a Koren_tube model from the lib. For the EC86 I used another model.

Don't think about the 1 mH-transformer, it's only for testing here.

I don't understand why the EC86-transient-analyse is succesful and the EC81 with the Koren_Tube-model in nearly the same circuit not.

thanx, best regards, Leo

In message <j55dke+dhss@...>, dated Sun, 18 Sep 2011, Charly Engineering <charly020664@...> writes:

I asked here for a model for the EC81, Suusi Malcom-Brown-B was so kindly to add the model to the Koren_tubes.cir-lib.-

Now I have the problem that a transient analyse delivers curious results.-

Everything delivers curious results. You have just a 1 mV input signal, which at low frequencies is attenuated further by the 18 pF capacitor and the 1 meg resistor, and the EC81's input capacitance.

Then you ac sweep goes to 500 MHz, at which frequency the 1 mH anode load has an enormous impedance and is quite impracticable.

I'm not very experienced with tubes, so I've uploaded the EC81-test-files to the folder temp.

It would help if you told us what you are trying to make a simulation of.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.