Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- LTspice
- Messages
Search
Re: Multiple plot panes
Tony Casey
--- In LTspice@..., John Woodgate <jmw@...> wrote:
Confucius say: Things remain hidden mostly for want of looking. :-) |
Re: Multiple plot panes
John Woodgate
In message <j54t57+aisu@...>, dated Sun, 18 Sep 2011, Tony Casey <tony@...> writes:
I've uploaded to File>Temp a screenshot of what you need to change to banish your greys.Thank you. Yet another hidden wonder! -- 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. |
Re: model, subckt tube EC81 = 6R4
John Woodgate
In message <4E75F5EB.8040605@...>, dated Sun, 18 Sep 2011, Ganesan <dg1@...> writes:
Thanks.. i think some tubes used to carry plate current curves for different heater powers.. If going to 5.55 volts instead of 6.3 doublesThe loss, and increased variability between samples, of performance is quite significant, and longer life is not assured, because 'cathode poisoning' (contamination by outgassed contaminants) is more of a problem at lower cathode temperatures. The best way of lengthening life is 'keep it cool and limit the switch-on surge in heater current'. -- 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. |
Re: model, subckt tube EC81 = 6R4
John Woodgate
In message <[email protected]>, dated Sun, 18 Sep 2011, Suusi M-B <smalcolmbrown@...> writes:
In the real world there is quite a difference between individual valves of the same typeThey are a sort of FET, after all! (;-) -- 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. |
Re: Ho do I Measure RMS AC riding on DC signal?
Kudos Tony,
Your response is extremely well written - clear and lucid, employing a keen understanding of the minutiae of LTspice to thoroughly answer Landrum's somewhat veiled request. Bravo for for correctly using the b-source time step control parameters, tripdv and tripdt - most people miss that. -- a.s. PS: Got your email regarding the improvement of Help. I am going to be incommunicado for a few days, but anyway I wanted to wait to see what response Lewis gets from Mike regarding permission to copy the existing Help to the LTwiki as a foundation upon which to build our own expanded Help colossus. :) --- In LTspice@..., Tony Casey wrote: --- In LTspice@..., Landrum Haddix wrote:I've been measuring lots of ripple voltages on DC power supply You questions are somewhat ambiguous, since there is no suchWhen the occasional need for this operation arises, my method is to zoom in on either an integral number of cycles or a large number of non-aligned cycles and ctrl-left-button click on the trace label to read the average value of the trace. I then edit the waveform expression to subtract this exact amount. Alternatively, you can carry on doing it your way, but with the |
Re: Multiple plot panes
Tony Casey
<snip>
Yes, that's what I meant. Time to upload, clearly. See the zip archive</snip> Hello John, I've uploaded to File>Temp a screenshot of what you need to change to banish your greys. Regards, Tony |
Re: model, subckt tube EC81 = 6R4
Ganesan
Thanks.. i think some tubes used to carry plate current curves for different heater powers.. If going to 5.55 volts instead of 6.3 doubles the tube life, very few wouldn't do it..
cheers AG In the real world there is quite a difference between individual valves of the same type The model that I created was derived from the Phillips / mullard 1968 book graphs. There is no provision for varying the heater voltage. The heater is assumed to be 6.3 volts DC or 6.3 volts AC (rms) No model is perfect, just an approximation that is good enough. The model was derived from the plate current vcs plate voltage graph for different grid voltages. Using the below data points. The data points are loaded into a matlab solver and the model generated. Vplate = [ 50 50 50 50 50 100 100 100 100 100 100 150 150 150 150 150 200 200 200 200 200 200 250 250 250 250 250 300 300 300 300 300 300 300 300 ]; Vgrid = [ 6 4 2 0 -2 4 2 0 -2 -4 -6 0 -2 -4 -6 -8 -2 -4 -6 -8 -10 -12 -6 -8 -10 -12 -14 -8 -10 -12 -14 -16 -18 -20 -22 ]; Iplate = [ .0345 .026 .0185 .010 .004 .044 .035 .024 .015 .0073 .0025 .0415 .030 .020 .0118 .006 .048 .037 .026 .0175 .0105 .007 .043 .0325 .023 .0152 .0095 .050 .0388 .029 .021 .014 .009 .0055 .003 ]; Hope that answers your questions. Suusi Malcolm-Brown |
Re: Multiple plot panes
Tony Casey
--- In LTspice@..., John Woodgate <jmw@...> wrote:
I have mine this month too, but there's at least another 19days and 9.5 hrs left for me to do it. :-) |
Re: model, subckt tube EC81 = 6R4
In the real world there is quite a difference between individual valves of
toggle quoted message
Show quoted text
the same type The model that I created was derived from the Phillips / mullard 1968 book graphs. There is no provision for varying the heater voltage. The heater is assumed to be 6.3 volts DC or 6.3 volts AC (rms) No model is perfect, just an approximation that is good enough. The model was derived from the plate current vcs plate voltage graph for different grid voltages. Using the below data points. The data points are loaded into a matlab solver and the model generated. Vplate = [ 50 50 50 50 50 100 100 100 100 100 100 150 150 150 150 150 200 200 200 200 200 200 250 250 250 250 250 300 300 300 300 300 300 300 300 ]; Vgrid = [ 6 4 2 0 -2 4 2 0 -2 -4 -6 0 -2 -4 -6 -8 -2 -4 -6 -8 -10 -12 -6 -8 -10 -12 -14 -8 -10 -12 -14 -16 -18 -20 -22 ]; Iplate = [ .0345 .026 .0185 .010 .004 .044 .035 .024 .015 .0073 .0025 .0415 .030 .020 .0118 .006 .048 .037 .026 .0175 .0105 .007 .043 .0325 .023 .0152 .0095 .050 .0388 .029 .021 .014 .009 .0055 .003 ]; Hope that answers your questions. Suusi Malcolm-Brown -----Original Message-----
From: LTspice@... [mailto:LTspice@...] On Behalf Of Ganesan Sent: 18 September 2011 12:25 To: LTspice@... Subject: Re: [LTspice] Re: model, subckt tube EC81 = 6R4 Most vacuum tubes will work with ac or dc on their filaments ( some will live a litle lesser under dc heating)... So the plate current is proportional to the heat generated in the filament until maximum emission is reached..( this is where most people use it).. Lifetime can be improved at lower levels of heating , albeit with some loss of gain.. My question is, Whether the plate current to heater coupling is correctly modeled through an rms function ? Cheers AG On 9/18/2011 5:49 AM, Dave wrote:
------------------------------------ Yahoo! Groups Links |
Re: Multiple plot panes
John Woodgate
In message <j54n5o+ehah@...>, dated Sun, 18 Sep 2011, Tony Casey <tony@...> writes:
But then, life is short...YTM; I'm trying to do 3 months accounts for the VAT return! -- 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. |
Re: Multiple plot panes
John Woodgate
In message <j54mi7+uvcb@...>, dated Sun, 18 Sep 2011, Tony Casey <tony@...> writes:
I'm sorry, I misunderstood your question because you used the word "pane" instead of "window". In LTspice, the Waveform Viewer understands "pane" to mean another set of axes within the same viewer window.Yes, that's what I meant. Time to upload, clearly. See the zip archive Pos and neg doubler rectifiers.zip It looks better if you 'Tile vertically', which the .plt file apparently doesn't save. -- 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. |
Re: Multiple plot panes
Tony Casey
--- In LTspice@..., "Tony Casey" <tony@...> wrote:
John, It occurred to me that there is a way around the problem arising when setting active and inactive windows to the same colour. There's a registry hack that can cause the window focus to follow the mouse position (a la Xmouse), so there's no confusion (ha ha). I can't remember where to get at it directly in the registry, but the Microsoft Add-on "Tweak UI" is able to change all kinds of details like this without having to dive into the registry. But then, life is short... Regards, Tony |
Re: Multiple plot panes
Tony Casey
--- In LTspice@..., John Woodgate <jmw@...> wrote:
Hi John, I'm sorry, I misunderstood your question because you used the word "pane" instead of "window". In LTspice, the Waveform Viewer understands "pane" to mean another set of axes within the same viewer window. The problem you want to fix, is down to the OS, not the application. To fix your issue, you will need to change the graphics colour settings (assuming WinXP): Right-click on desktop Properties>Appearance>Advanced>Item>Inactive Titlebar .. and change to the same colour as the Active Titlebar. I don't recommend it, though, as you will then not be able to tell which application (window) actually has focus. But you could set the colours so they were very similar instead of just grey, or just make it temporary. Regards, Tony |
Re: model, subckt tube EC81 = 6R4
Ganesan
Thanks,,
toggle quoted message
Show quoted text
cheers AG On 9/18/2011 5:49 AM, Dave wrote:
|
Re: model, subckt tube EC81 = 6R4
Ganesan
Most vacuum tubes will work with ac or dc on their filaments ( some will
toggle quoted message
Show quoted text
live a litle lesser under dc heating)... So the plate current is proportional to the heat generated in the filament until maximum emission is reached..( this is where most people use it).. Lifetime can be improved at lower levels of heating , albeit with some loss of gain.. My question is, Whether the plate current to heater coupling is correctly modeled through an rms function ? Cheers AG On 9/18/2011 5:49 AM, Dave wrote:
|
Re: Ho do I Measure RMS AC riding on DC signal?
Tony Casey
--- In LTspice@..., Landrum Haddix <lhaddix@...> wrote:
Hello Landrum, You questions are somewhat ambiguous, since there is no such thing in this context as an RMS AC waveform. If you just want to look at the AC portion of the waveform in the viewer, you have several choices: - Change the Y-axis plot range to only show the portion of the waveform, you're interested in. This method has the disadvantage that every time the viewer re-plots, it will autoscale so you will have to repeat the scaling exercise. An alternative is to save a .plt file with your preferred axis settings, and reload it each time the waveform is re-plotted. Hint: assign a Hotkey to do this. I use [spacebar] like others have mentioned recently - Plot the quantity V(ACnodename)-DCOffset (where DCOffset is the numerical value for the estimated offset. Of necessity, this will be a manual process, as the waveform viewer has no way of knowing what you mean it to plot. Alternatively, you can carry on doing it your way, but with the same advantages and disadvantages as AC-coupling with a real scope. If you actually want to measure the rms value, as suggested by the title of your post, you can use post-processing scripts to calculate that from the simulation data. Add the following lines in a SPICE directive: .meas TRAN Vavg avg V(out); calculates the DC offset .meas TRAN Vrms rms (Vavg-V(out)); calculates rms after substracting the average You will find the results of these calculations in the logfile after each simulation. Of course having found the average value by this means, you can then substitute its value into your viewer plot expression. This is helpful since if you are also performing a .stepped simulation, the Waveform Viewer won't calculate the average and rms values of a waveform. One more tip: if the AC voltage is small compared to the DC offset, you will also need to add the directive: .option plotwinsize=0 ...too, or the waveform compression will distort the ripple voltage and the rms calculation will be wrong. There's also a really nerdy way to display exactly what you want to see in the waveform viewer, but it requires some subterfuge, and can only show the ripple voltage right at the end of your tran time, since it calculates the DC offset on the fly. This will only work if your DC offset is stable over time. You can find this example as RMS_Value.zip in Files>Temp Hope this helps. Regards, Tony |
Re: model, subckt tube EC81 = 6R4
Ganesan
They look cool/ Thanks..
toggle quoted message
Show quoted text
Cheers AG.. On 9/18/2011 5:49 AM, Dave wrote:
|
Re: model, subckt tube EC81 = 6R4
They are included in LTSPICE, just hit the insert component menu and
toggle quoted message
Show quoted text
navigate to the "misc" folder... . -----Original Message----- |
to navigate to use esc to dismiss