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Re: Help! How do I do find maximum signal easily!
Hi Macy,
Problem with the versions of multiple files, is that by necessityPersonally I use version control systems for all my code, so I never have any doubt as to what is going on. Cheers, Dave |
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Re: Help! How do I do find maximum signal easily!
Andy, Thanks I was just going to try using the + at the start of shorter lines.
Actually, the humongous long line is easier to cope with than I thought. Now that David pointed out I can ctrl, right click to toggle between .ac and .noise of ANY types. I only have to zoom in on the actual component schematic once. I'm still surprised about the noise analyses so closely matching my measurements. Usually in the world of noise, I'm happy if hit within magnitudes and ecstatic at multiples, but within 3% ??!! Now THAT's just impressive. With that kind of accuracy, LTspice is going to save a LOT of breadboarding time. --- Andrew.Ingraham@... wrote: From: Andy <Andrew.Ingraham@...> To: LTspice@... Subject: Re: [LTspice] Re: Help! How do I do find maximum signal easily! Date: Mon, 15 Jul 2013 13:18:03 -0400 Macy wrote: I like the idea of 'including' the file with everything in it then I can modify and control a bit better, BUT that separates the design into twoWell, you've got a choice. You can either (1) keep everything on the schematic, or (2) move stuff off the schematic into a separate file. Pick one approach or the other, and live with it. You can't do neither. With it on the schematic, obviously, if you have a lot of text, it's going to take up a lot of schematic space which shrinks the full view. With it off the schematic, obviously, you have to deal with two or more files. Create a new project folder for each schematic, and then you are less likely to lose track of the second file. The stuff on the schematic (or in a text file) doesn't need to be one long line. Break it into shorter lines, with a "+" as the first character on all lines after the first. If you stick with approach (1), that might make it not quite so huge. .ac LIST freq freq freq ... + more freqs freq freq ... + more freqs freq freq ... etc.... When entering or editing the .ac or .noise lines on the schematic, be sure to use the Ctrl-M trick to insert line breaks. You need those lines to be kept together as one unit, not as independent SPICE directives. You might also go into the LTspice Control Panel and change the font size. This affects all text on the schematic (and all LTspice schematics you edit), and it has a limited range so it might not make enough of a difference. Andy |
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Re: Help! How do I do find maximum signal easily!
David,
YES! ctrl, right click works! didn't know about that ability. [Mike, thanks for anticipating] Problem with the versions of multiple files, is that by necessity they all have the same name! Makes it really difficult to make certain that like is with like. Right now I solve that by 'freezing' them as a set into either a folder with a different name, or by zipping all together with a version/date code. Next, I'll try the included LIST.txt file and see what happens, I like the ability to make comments, since memory rarely lasts a month. ;) --- dwh@... wrote: From: David Hawkins <dwh@...> To: LTspice@... CC: Macy <macy@...> Subject: Re: [LTspice] Re: Help! How do I do find maximum signal easily! Date: Mon, 15 Jul 2013 09:17:47 -0700 Hi Macy, To bounce between analyses I tried the right click on the comment,If the SPICE directive is something like .step or .param, you can just right click. If the SPICE directive is something that the simulation GUI normally deals with, then the GUI pops up, unless *you press ctrl* and right-click :) I also tried a trick I used to do on the old version of LTspice - putNo need to, it already exists. I like the idea of 'including' the file with everything in it then IC'mon man, surely you have created designs with hundreds of files. What do you do when you layout your PCB, you've got a schematic, a PCB file, a zillion symbols, etc.? Just use two files. You've got a design that consists of graphics and text, just put the text in a text file :) Cheers, Dave |
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Re: Current source behaviour in 'active load' mode
--- In LTspice@..., "redblack001" <news@...> wrote:
More generally, is there a better way to model a PSU with aThere are probably dozens of ways to do this in LTspice. Here is one way that uses just one device (a V-I table I-source): I1 0 1 TBL(-5 0 {1u-5} 1 0 1) ; 5V 1A PSU with 1uV of droop R1 0 1 R=1u+time**2 ; behavioral resistor used as a test load .tran 10 |
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Re: Current source behaviour in 'active load' mode
Hi.
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Look: Ideal voltage source current-limit. Series resistance=0. The model is made for LTspice. Bordodynov. 16.07.2013, 15:11, "redblack001" <news@...>: Hi, |
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Current source behaviour in 'active load' mode
Hi,
I've been playing with the current source element with the 'active load' box checked. I place this in series with a voltage source and a resistive load (e.g. to model a PSU with current limit) and ramp up the voltage. The load current flattens out as expected once it reaches the current source set point, but below this point the current source behaves as a resistor with value (1/I_set). Is there any way to change this behaviour, or does it behave this way for compatibility with other variants of SPICE? More generally, is there a better way to model a PSU with a current limit that doesn't impose any voltage drop until the current limit is reached? TIA R. |
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Re: RF Frequency Tripler design
Jeff,
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Well, 2 diodes connected anode to anode and cathode to cathode would a parallel connection. Anti-parallel is 2 diodes connected anode to cathode in parallel.The additional diode results in the suppression of even order products, the enhancement of odd order products, and the elimination of the bias resistor. Jerry --- In LTspice@..., Jeff Walden <jwalden@...> wrote:
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Re: RF Frequency Tripler design
Long long ago and far far away, I designed varactor triplers for 100 watt
transmitters to go from 150 MHz to 450 MHz. Even in the day I had some kind of model for the varactor for the pre-SPICE analysis program. The fundamental idea was to generate harmonics via the diode followed by a dual helical coil filter. Like I said ... long long ago. The performance of the varactor is directly influenced by the minority carrier lifetimes of the device. The vendor once "improved" the product. This was shortening the minority carrier lifetime ... aka switching faster. Needless to say this prevented my tripler from working. Zapping the parts in a van degraff generator sufficiently damaged the higher performing varactors to acceptably allow my tripler to work again. The product line was shut down until the quickest solution was found. Ok. So off subject, but this reminded me of the past. What are anti-pallell PIN diodes? Conceptually. On Mon, Jul 15, 2013 at 6:12 PM, jmulchin1 <jmulchin@...> wrote: ** -- Jeffrey L Walden EMC/SI RF analysis and product development jwalden@... (866)547-5365 [Non-text portions of this message have been removed] |
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Re: AD734 Multiplier: Basic Circuit: ac simulation uses parameters from transient
You also need to realize that an .AC analysis is a small-signal linearized analysis. The multiplier, which is an inherently nonlinear device, is presumably linearized at the operating point, and treated as a linear gain block. Thus, if you were to input (say) 100 kHz to both input ports (as you have), you would not find any 200 kHz on the output ... and LTspice would not plot the amplitude of the 200 kHz (that this chip actually outputs) ... because an .AC analysis does not generate sum-and-difference frequencies. If anything, it will only tell you how much of the 100 kHz goes through because of leakage/imbalance, and because of the fact that the other port's bias voltage was not 0.0V. One might even question if you can do an .AC analysis at all. Whether you get anything meaningful, depends on what's inside the model for this part. Depending on how they modeled it, it might work correctly in a .TRANsient analysis, but not in an .AC analysis. I'm just sayin'. Regards, Andy |
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Re: AD734 Multiplier: Basic Circuit: ac simulation uses parameters from transient
Maren (distheo@...) wrote:
a) Why is the .ac simulation influenced at all by the parameters of the transient simulation?In an .ac analysis, LTspice first needs to find the operating point. All voltage and current sources are set to their values at t=0. Since you specified a SINE source with a phase shift of 45 degrees, the t=0 value is 0.707* 3.0 = 2.12132V. Regards, Andy |
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Re: Determining the value of a variable at time t-1
The idea I will give you is to open Help in LTspice; Then go to LTspice > Circuit Elements > B. Arbitrary Behavioral Voltage or Current Sources. Scroll down and find the first table of functions. Andy |
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Re: Help! How do I do find maximum signal easily!
Macy wrote:
I like the idea of 'including' the file with everything in it then I can modify and control a bit better, BUT that separates the design into twoWell, you've got a choice. You can either (1) keep everything on the schematic, or (2) move stuff off the schematic into a separate file. Pick one approach or the other, and live with it. You can't do neither. With it on the schematic, obviously, if you have a lot of text, it's going to take up a lot of schematic space which shrinks the full view. With it off the schematic, obviously, you have to deal with two or more files. Create a new project folder for each schematic, and then you are less likely to lose track of the second file. The stuff on the schematic (or in a text file) doesn't need to be one long line. Break it into shorter lines, with a "+" as the first character on all lines after the first. If you stick with approach (1), that might make it not quite so huge. .ac LIST freq freq freq ... + more freqs freq freq ... + more freqs freq freq ... etc.... When entering or editing the .ac or .noise lines on the schematic, be sure to use the Ctrl-M trick to insert line breaks. You need those lines to be kept together as one unit, not as independent SPICE directives. You might also go into the LTspice Control Panel and change the font size. This affects all text on the schematic (and all LTspice schematics you edit), and it has a limited range so it might not make enough of a difference. Andy |
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Re: Help! How do I do find maximum signal easily!
Hi Macy,
To bounce between analyses I tried the right click on the comment,If the SPICE directive is something like .step or .param, you can just right click. If the SPICE directive is something that the simulation GUI normally deals with, then the GUI pops up, unless *you press ctrl* and right-click :) I also tried a trick I used to do on the old version of LTspice - putNo need to, it already exists. I like the idea of 'including' the file with everything in it then IC'mon man, surely you have created designs with hundreds of files. What do you do when you layout your PCB, you've got a schematic, a PCB file, a zillion symbols, etc.? Just use two files. You've got a design that consists of graphics and text, just put the text in a text file :) Cheers, Dave |
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Re: Help! How do I do find maximum signal easily!
now there are 'comments' on the schematic
.ac dec 500 10 100k .noise V(out) Vsource dec 500 10 100k .ac LIST this goes forevers..... .noise V(out) Vsource LIST ditto..... [Thanks for suggesting LIST. It also works in the noise analysis.] The last two are so long that when I open the schematic I get almost NOTHING on the screen - a bit of blue smidgeon on the left and tiny little blue dots going across the page. At first, I thought LTspice broken. So I have to do the + circle about where I think the schematic is located, and voila! I get enough I can see it to position a bit better. To bounce between analyses I tried the right click on the comment, convert to spice command, which works, but CANNOT UNDO THAT! I had to ctrl-c the line and put it back as a comment, and then scissor cut the spice command to change the spice command. I also tried a trick I used to do on the old version of LTspice - put an asterisk on the start of the spice command line to 'turn it off', but that no longer works. Mike, perhaps in the next wish list put in an easy way to toggle between spice and comment lines. I like the idea of 'including' the file with everything in it then I can modify and control a bit better, BUT that separates the design into two pieces, which may, or may not, be kept together. I know, I know sloppy paperwork, but still something always happens and I'm not absolutely certain that x1 schematic was used with x1 text file. Thus, as you can see, there is a way to get around on this thing, but is there an easier way? --- dwh@... wrote: From: David Hawkins <dwh@...> To: LTspice@... Cc: Macy <macy@...> Subject: Re: [LTspice] Re: Help! How do I do find maximum signal easily! Date: Fri, 12 Jul 2013 16:07:44 -0700 [snip] and the .ac using specific values requires storing on theWhy not put all the relevant text into file, and then .include it. It makes the schematic look nicer, and allows you to add header comments to the file along with relevant comments throughout the file. Cheers, Dave |
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Re: Locked files
Yes, all the files are in the location you mention. I will copy everything to a desktop folder and then see if I can copy that. Thanks!
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--- In LTspice@..., John Woodgate <jmw@...> wrote:
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Re: 3722 Power Supply Problem
RL,
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Thank you for taking a look but I still have an issue. The bridge nodes that you renamed now disconnected the ZVS circuit of the chip because the nodes have been renamed to SWAB and SWCD the SWT and SWB nodes are no longer connected and are left floating. Also when the when the input power supply drops to 18V the regulation of the 165V rail is not kept. I would also appreciate it if you could tell me how you came to derive all of the compensation values. Thanks for your help. Leo --- In LTspice@..., legg@... wrote:
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