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Post by Gary Lecomte on Oct 11, 2008 20:01:44 GMT -8
Linear Technologies produces some Very good Integrated devices. I use many of there devices, but they are NOT Cheap.
As to that or any Simulation Software, It may be good for you and many others. But in most cases, I can actually Prototype a design, Faster than I can enter it into a spice program. And test it for real for real results.
Previously I have had too may problems with Spice Simulations, especially when your limited to only certain parts.
As to Substituting Simular parts, that usually won't produce the same results as the designated part.
Texas Instrument also has Simular, Very Good Spice programs. But Like LT, they are Specific to TI Parts.
But I Guess, Whatever works for you is OK.
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rmeyn
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Post by rmeyn on Oct 13, 2008 6:45:52 GMT -8
The parts limitation problem has always been around. Only recently, I figured out how to create my own parts when they are missing. You have to be able to read data sheets and carefully enter critical parameters. You never really know whether the model you have created is working exactly as intended. That is one of the reasons I like LTspice. Their models have been tested thoroughtly, In fact LTspice is used to design their chips before making prototypes. As for substitution, I agree that you can run into trouble here if you don't know what you are doing. Diodes, capacitors, zeners, transistors are less problematic if you match parameters carefully. rmeyn
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Post by lamazoid on Oct 14, 2008 12:01:22 GMT -8
That's cool. Does it have models for LT3485 and other ICs from this series (photoflash charger controller) ?
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rmeyn
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Post by rmeyn on Oct 16, 2008 4:46:44 GMT -8
Yes, the LT3485 is available. You will find it under "power products", I believe. rmeyn
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rmeyn
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Post by rmeyn on Oct 19, 2008 6:04:09 GMT -8
Iamazoid, Did you have a chance to download LTspice and simulate the LT3485? rmeyn
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rmeyn
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My primary interests are electronics, sailing, bowling, and camping
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Post by rmeyn on Jan 28, 2009 20:20:15 GMT -8
Well, a little update, for those interested, concerning my LTspice simulations. A number of years back I took several home study courses from Heathkit, ending up with electronic circuits. I thought for fun I would run some of them with the simulator and see how the results compared with my actual trainer/oscilloscope results. I was amazed! I am ever more certain, that if you are a designer, the simulator is the way to try out ideas. No more fussing to lock in a scope pattern. A few clicks of the mouse and you have a steady pattern to look at. Components can be changed in seconds, not minutes. The ability to run simulations with varying inputs (different sweep analyzes) is priceless. Anyone else out there had similar experiences? rmeyn
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Post by lamazoid on Jan 29, 2009 0:18:39 GMT -8
I will try this out, but not before i get real components and make the ciruit. I want to make small low-input DC-DC converter based on this LT3845. But i can't get this IC locally, i should order it and wait 1-2 months before arrival And the same problem with other parts like modern film capacitors (Epcos, Rifa, etc.)
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rmeyn
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Post by rmeyn on Jan 29, 2009 5:14:42 GMT -8
But the point is that you can try out your design without the components. Ltspice has those components in their library. You really need to try it out. Why does it take so long to get components? Is is import regulations and exchange rate problems? Maybe I can help. rmeyn
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Post by lamazoid on Jan 29, 2009 12:19:26 GMT -8
I want to compare the result with simulation to understand it better and find "underwater stones". Now i have one project to try, but it's not with Linear ICs. Maybe if i find some time i'll try to simulate it in Multisim or something... and post here. As to components, the problem is they generally don't sell small quantities to regular persons (only thousands and for companies), there are only couple companies that do so. Most of our local parts stores are working for repair, so they sell only parts needed to repair TV, microwave, etc. and not just any parts for hobbyists So i need to order it from Moscow (russian capital) which is far away from where i live and i should wait for long time...
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Post by lamazoid on Apr 9, 2009 10:22:36 GMT -8
Richard, you help required on modelling transformers in SPICE. I'm trying to make a model of a simple blocking oscillator, since i can't find anywhere information how to design them other way the purpose of oscillator is fluorescent tube driving for backup light / camping. I have built this device and its real performance is far from what simulation says. Now, where is the mistake? My guess it's a transformer since other parts are equal. I've made it using 3 ideal inductors to simulate coupling , and 3 nonlinear inductors to simulate windings. Is this correct? The real transformer is made on 22mm POT core and it has the same inductances and turns number as shown on model.
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rmeyn
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Post by rmeyn on Apr 9, 2009 13:45:37 GMT -8
Iamazoid, I would be happy to work on it. Hopefully Gary can consult as well. I notice no values for L4, L5, and L6. Did you run this on Pspice or Ltspice? Richard
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Post by Gary Lecomte on Apr 9, 2009 16:01:23 GMT -8
Iamazoid, I would be happy to work on it. Hopefully Gary can consult as well. I notice no values for L4, L5, and L6. Did you run this on Pspice or Ltspice? Richard STRANGE SCHEMATIC, Why the Coils in Parallel? L1 & L6 L2 & L5 L3 & L4 That Doesn't make sense to me. Gary
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Post by lamazoid on Apr 9, 2009 21:33:50 GMT -8
Iamazoid, I would be happy to work on it. Hopefully Gary can consult as well. I notice no values for L4, L5, and L6. Did you run this on Pspice or Ltspice? Richard Sorry, i forgot to mention it. It's LTSpice SWCad III. The values for L4, L5 and L6 are above the schematic - 3 long lines of text. A have one electronic textbook which says it's a way to simulate real transformers, but i'm not sure it's the only and the right way. Parameters are specified exactly instead of "inductance value" string in coil properties. Hc, Br, Bs etc., are magnetic properties of the real core material which i've used, N is the number of turns.
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rmeyn
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My primary interests are electronics, sailing, bowling, and camping
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Post by rmeyn on Apr 10, 2009 6:09:59 GMT -8
The values for L4, L5 and L6 are above the schematic - 3 long lines of text. A have one electronic textbook which says it's a way to simulate real transformers, but i'm not sure it's the only and the right way. Parameters are specified exactly instead of "inductance value" string in coil properties. Hc, Br, Bs etc., are magnetic properties of the real core material which i've used, N is the number of turns. Thanks. I've played around before a little with magnetic properties of a pot core (think it was your design). I'll see what I come up with. Richard
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Post by Gary Lecomte on Apr 10, 2009 8:25:42 GMT -8
Does this schematic represent what your trying to Simulate? If So, I doubt you can do it, as your simulation program doesn't have a suitable symbol, with the appropriate data input. Mainly because the Coils/Transformers your using, Don't have Mutual Magnetic Fields.I have had this problem Many Times also. Gary
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