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Using parameters and functions when defining a plot
Is it possible to scale a trace by a parameter defined on the schematic? Like:? .param maxvolts=122, and then plot V(c1)/maxvolts . Such a thing works when adding the parameter statement to the plotdef file in the scad3.exe directory, but that is not very?handy because these constants aren't universal?(in the project directory would be better already). Likewise, I sometimes scale a plot by a computed number, say the max value of the current when doing an FFT. It would be nice if these constants could be evaluated before a plot is made ( V(c1)/max(V(c1)) or something like that? -marcel |
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differimproved
I uploaded differimproved.zip in /temp. It is a simulation of a simple audio amplifier. Somewhat to my surprise my modifications didn't lead to the expected decrease in THD. Checks with another simulator (NGSPICE) shows that the THD does decrease. It also showed that LTSpice is about 3 to 6 times slower than NGSPICE for this problem. Of course this can't be true :-) Does?anybody spot the problem?on this schematic? There must be "something one is not supposed to do" on it. -marcel |
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Re: How can I make my simulation oscillate like my poorly designed PC board does?
The Miller cap is not added to stop the oscillation, but to slow the switching edges.? You can see the edge slow-down effect in the uploaded file (Files/Temp folder).? The simulation has a pair of the circuits, one with, and one without the 300pF cap that performs the slow-down.? Without the slow-down, there is a 30MHz spike in the PCB emissions scan, related to the edge rate of the switching waveform.? By adding the cap, along with a 47 ohm resistor in series with my gate drive, the slower edge rate lowers the emissions at that frequency by about 10dB, which is my goal.? Of course, this allows for any high-Q circuit strays to try to oscillate, which is what I'm trying to simulate.
I've tried your suggestions, but the simulation still shows no sign of oscillating.??Am I still doing something wrong with my quest for oscillation? I've uploaded a version of the file "Oscillating Miller FETs 02.asc" to the files/temp directory.? This file has my interpretation of your suggestions, but I still can't make it oscillate.? I've tried a variety of component values and several different FETs, looking for a hint of oscillation.? Can somebody make it oscillate for me? thanks, Carl
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Re: In situ changing of a MOSFET Rdson in the subcircuit
¿ªÔÆÌåÓýHello Waynel,please have a look to these Application Notes: In : (a very interesting collection) ->Discretes ->FETs (97) ->Mosfets (86) ->AN-7532 ->AN-7533 ->AN-7534 There are a lot of MOSFET and IGBT models at the homepage of this company which have the electrical and thermal function: There are also such models available from other companies. Please give me an information if such models works with LTspice. Note: Mr. Alain Laprade which was one of the authors of these FAIRCHILDSEMI application notes is currently "Senior Applications Engineer at ON Semiconductor" Best regards Bernhard Valouch Germany -- Bernhard Valouch |
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Re: Is the Group down?
Ian Field
Yahoo is being its normal self - as usual!!! I signed up for LTspice posts, but users of other groups that didn't are now complaining about an inbox full of LTspice messages. Yahoo needs a web designer that wasn't dropped on their head when they were little. On Thursday, 29 May 2014, 20:56, "Dan Andersson dan@... [LTspice]" wrote:
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Re: Is the Group down?
Yahoo's gone mental. Other groups are affected to.
//Dan, M0DFI On Thu, 29 May 2014 22:12:32 +0300 "Vlad imbvlad@... [LTspice]" <LTspice@...> wrote: Hello |
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Re: Is the Group down?
Same for me. I see some note while waiting about "waiting for proxy." --s.a.hill (new to group) On Thu, May 29, 2014 at 3:12 PM, Vlad imbvlad@... [LTspice] <LTspice@...> wrote:
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Is the Group down?
Hello
I keep getting errors whenever I try to access the web page of the Group, no matter if it's the files or the conversations, but I seem to be able to post replies from within GMail. Is this a general (hopefully temporary) flaw? Vlad ______________________ ltspicegoodies.ltwiki.org -- 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. |
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Re: Clipping a Universal op-amp
On a second thought, the "sw" only might do (it has "vt" and "vh"),
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but if an additional delay is needed (to avoid "time step too small: errors), the comparator will come in handy. Vlad ______________________ ltspicegoodies.ltwiki.org -- 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. I don't really understand your purpose but, given what you have said:OK: Now can I rig a feedback which essentially lies dormant until theyou could make use of a comparator (use the Schmitt A-device with "vt=50m |
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Re: Li-ion BAttery models
Thx Woody
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Re: Clipping a Universal op-amp
I don't really understand your purpose but, given what you have said: > OK: Now can I rig a feedback which essentially lies dormant until the > error voltage exceeds maybe 50mV, then jumps in to force balance?
you could make use of a comparator (use the Schmitt A-device with "vt=50m vh=0") and a VCVS (element "sw") with proper Ron/Roff. I'll just leave the "how" and "why" for yourself. 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. |
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Re: Clipping a Universal op-amp
Well, suppose you have a gain 2 non-inverting setup. Vin+ > Vdd/2 means the op-amp cannot actually make the summing node Vin- anything like Vin+.
So Vdd=5, Vin+=5, Vin- = B.rail = 2.5: error is +2.5 - not a "working/normal" error voltage but an ERROR voltage (big time). So the output hits the rails. As Vin + gets higher, the error voltage Vin+ - Vin - rises from a normal "enough to drive the loop via AB" to something crazy lit 1, 2 or more volts. OK: Now can I rig a feedback which essentially lies dormant until the error voltage exceeds maybe 50mV, then jumps in to force balance? Yes - the output will not then be 'correct'. But it would be wrong anyway, and I at least the output is not at the rail. |
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Re: Model for H11L1 optocoupler
John Perkins wrote: ? ?"Does anyone know where I can get a model for the H11L1 optocoupler?" There is one in this group, in the Files section. ? ?"There where some messages about this part a few years ago (2011), and it appears that someone came up with a model and posted it, but it is no longer available." I just downloaded it. ?I don't know anything about the H11L1, but the schematic seems appropriate for an opto-coupler. ?Anode, Cathode, Out, Gnd, and Vcc pins. ?It looks like it is meant to be used as a subcircuit, a lower-level hierarchical page. The ZIP file that is in the same directory ("AN3006_60Hz_4.zip") has a slightly different version of the same H11L1 schematic, plus an LTspice symbol
?for it ? that can be used to place it on your schematic for simulation.Regards, Andy |
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Re: Li-ion BAttery models
I need Li-ion battery model that can be simulated in lt-spice (4.2v) rather than charging ckt...If any1 had it..plz post it to me Thanking u On Thursday, May 29, 2014 8:27 PM, "Andy
Andrew.Ingraham@... [LTspice]" wrote:
?
Lohith Vamsee wrote: ? ?"...?I need a li-ion battery model inorder to simulate.
? ? Can u suggest me some links or models?"
There may be a few in our group's Files section. ?Download the Table of Contents file (see instructions on the group's main webpage) and search it for "lithium". ? A few matches come up. ?It's not much, but you might find one of them works.
Regards,
Andy |
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Re: How can I make my simulation oscillate like my poorly designed PC board does?
I really have to bite my tongue here over Carl's poor aim at uploading files.
LTspice should be able to reproduce the transitory MOSFET oscillation just fine as long as the circuit model is reasonably correct.? The rule of thumb for stray inductance is about 10nH per centimeter, so throw out all the strays from your schematic and start over as follows. Add 5nH directly in series with each MOSFET terminal to represent the lead inductance.? Add 100nH in series with the 50 ohm drive to the gate to account for your poor layout.? Add 20nH in series with the 300pF capacitor.? You also could add 5pF to ground from the junction of the 100nH drive and 5nH gate lead inductance. Now you should see the oscillation.? Note that the exact values given above don't matter unless you wish to match exactly the frequency and amplitude of the oscillation.? If this circuit were running from a higher drain voltage, the oscillation would be large enough to rupture the gate and destroy the device (try increasing the power supply to 25 volts and see what happens). The standard cure for this problem is to insert a damping resistance in series with the drain-to-gate capacitor that has a value equal to or somewhat less than the gate drive resistor (20 to 50 ohms in this case). ---In LTspice@..., <Andrew.Ingraham@...> wrote : Carl wrote: ? ?"I've uploaded my circuit (Oscillating Miller FETs.asc) for your viewing pleasure." Unfortunately you uploaded it to the wrong Yahoo Group! Please re-upload it to THIS group, the [LTspice] group. ?The Files area in this group is the right place to put it, in the Temp directory. Regards, Andy |
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Re: cursor dialog in way of schematic
This is the problem
1. Maximise LTSpice 2. Maximise the schematic 3. You run it, add cursors. 4. Swap back to tab: It's a pain to have to close the dialog - and moving it won't always help, as you'l have already placed it where you wanted when looking at the plot. |
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cursor dialog in way of schematic
The cursor dialog shown on plots lives on top of the
schematic too: even in "full-screen" mode (not tiled, not cascaded). Surely it is not a good thing that the cursor dialog is visible when I change tabs in full-screen mode ? (It's fine in Tile or Cascade mode) Yes, sure "I can just delete or move it"... The way I see it, working full-screen (tabs at top) means "I want to see what the tab says over the full application window" not "I want to see all of the schematic and any dialogs associated with the plots". |
thutches