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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
John Woodgate
开云体育LTspice is good up to frequencies where you need to use distributed elements, which I suppose is about 1 GHz. It's not intended to be an optimiser. Is there anything a Smith chart can do that LTspice matrix methods cannot? ? With best wishes DESIGN IT IN! OOO – Own Opinions Only J M Woodgate and Associates Rayleigh England ? Sylvae in aeternum manent. ? From: LTspice@... [mailto:LTspice@...]
Sent: Thursday, August 4, 2016 5:34 PM To: LTspice@... Subject: [LTspice] Re: high frequency MHz and GHz range BJTtransistor or Mosfet ? ? This is not exactly relate to the original question. My question is how useful is LTSpice for RF design? I was an RF engineer, we use Microwave Office and using Smith Chart for matching and gain. I don't see LTSpice can help much in designing RF circuits(tuned circuit). Particularly when use start using distributed elements ( using stripline or microstrip to simulate inductors and capacitors). |
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
This is not exactly relate to the original question. My question is how useful is LTSpice for RF design? I was an RF engineer, we use Microwave Office and using Smith Chart for matching and gain. I don't see LTSpice can help much in designing RF circuits(tuned circuit). Particularly when use start using distributed elements ( using stripline or microstrip to simulate inductors and capacitors).
I am sure LTSpice can give you the answer if you fill in the values of the L R C, but it will not help you in optimizing the circuit which is the key for RF circuit. But you cannot guess the values. I use LTSpice for RF transistors only for wide band circuits where smith chart is not particularly useful. |
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
....for those of you new to "BJT land", I found this little tidbit* on youtube:
No Helmut they didn't have the German version (that I could locate anyway). W. Warren *( figured this website would appreciate this stuff, other sites I might have posted this on would have ??? barred me for spamming ; ) ? |
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Re: high frequency MHz and GHz range BJTtransistor or Mosfet
开云体育yes, but that’s the can. The mmbt918 in sot23 is in stock @ 4?@3k.? Much better deal than ?4. ? ? ? From: LTspice@... [mailto:LTspice@...]
Sent: Wednesday, August 03, 2016 11:47 PM To: LTspice@... Subject: Re: [LTspice] high frequency MHz and GHz range BJTtransistor or Mosfet ? ? Frank Mead wrote: "The 2n918, 2n5179, and the 2n2857 are still alive and well in Mouser database... they are still used..." ? Indeed they are listed. But did you check the prices and availability? At ?4 each for a 2N918, nobody's going to design it into anything; these are for maintenance only - mostly for military, and Central Semi are not the original manufacturer. They buy rights to old devices when discontinued by their originators. They're obsolete in the same sense as KT66s. [Stands back and awaits flames. ?:-) ?] ? Regards, Tony ?
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Re: Sub circuit heat dissipation not showing
Hello,
>?Helmut thanks for your answer. Much appreciated. Unfortunately, last night I replied with a detailed answer. I hit SEND but it isn't here ?? I don't understand. Humm.. I also miss two of my messages regarding AD830 from last night. They are still not there. It seems Yahoo had a problem last night.? >?BTW. What is the Poll button about?? There was a new poll a few days ago. I have deleted this poll, because it looked useless. There were two other polls which I had deleted before, because I read somewhere that the problem with list by "topics" could have to do with polls. Finally I found this is not true. The topics problem?is independent Best regards, Helmut ? |
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Re: "4 GROUP.zip" upload
PERFECT ANSWER!!! (shouted)?
 I appreciate the explanations, I will copy and save it for periodic reference I when screw up again.I'm sure I typed my message, but not sure I sent it or I did and yahoo went weird on me. Maybe my shout was loud enough in the upload to be heard in messages :) no!! ? You did very good by me ?and I thank you. Is there an easy or a standard way to make a model for these transistors that can be included in LIB/cmp/standard.mos? Jeff |
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Re: Sub circuit heat dissipation not showing
Helmut thanks for your answer. Much appreciated. Unfortunately, last night I replied with a detailed answer. I hit SEND but it isn't here ?? I don't understand. Humm..
Basically I said I uploaded the TIP142 sub circuit and I get a dissipation plot but not the power dissipation value. For that matter R2 doesn't even have dissipation value. I think in my original post I point out that the value (not the only the formula) is what I was looking for. Very frustrating that I typed such a detailed answer last night but it's not here! I'm at work so that about all the time I have. BTW. What is the Poll button about?? Also how do I get emails just on this conversation and not all the others in the LT Spice group. I must admit this group is very informative though. I just didn't want to fill up my mailbox. Thanks Again, Brad PS) hopefully this post will make it through!! ---In LTspice@..., <helmutsennewald@...> wrote : Hello, The power dissipation of the TIP142 from our Files section will be correctly displayed. TIP_142_test.zip ?? Here are a few more examples. Their power will be displayed too. All the Darlington transistors in my examples correctly plot power.? In therory there are subcircuits possible where LTspice doesn't plot the power due to special combinations of sources internally connected to the pins of a subcircuit. You should upload your files for a test. Best regards, Helmut ? ? |
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Re: Henry's current transformer problem
Andy and analogspiceman
Thank you for your replies. Actually, I am not sure what I was thinking for the path length = Ie! It should of course be Pi * D where D = (Internal Diameter + External Diameter)/2. Hence for my figures it is about 71.47mm, so Lm is 71.47m. Also I now realise that LTSpice has Hc specified in A/m and the Information I found for typical ferrites was 0.2 Oesteds which is about 15.9 A/m. So Hc for LTSpice = 15.9. I appreciate that there is a lot of variation in ferrite materials, but I am just trying to use a typical one that could be used for a Current Transformer, as I do not know which specific one has been used. Having clarified the above, I have one more question. Do you have any knowledge of how the actual VA of the Burden Resistor used versus the VA rating of a Current Transformer affects the accracy of the resuting Voltage? My thinking is that the higher the VA through the Burden and hence the Current Transformer's secondary coil, the hotter it gets and hence this affects the resulting Voltage as the core's magnetic properties dictate. Would that be correct or can you offer any more insights and/or provide any links to sources of information about this topic? Thanks and Regards Henry Kafeman ---In LTspice@..., <ai.egrps@...> wrote : Henry wrote: ? ?"I now believe the core of the CT is "ferrite"." ?FYI -- ferrites encompass a whole class of materials, with a widely varying range of magnetic characteristics.? Ferrites are often used as cores for "ferrite beads", chokes, and transformers, and there are many ferrite materials (or "mixes") to choose from. Andy |
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Re: Need spice model for IR TX and RX
...best* I can do Dhanabal:
?? <---data sheet ? <--SPICE and related modeling software at site W. Warren *(See if there is a usable model already in LTSPICE similar to those devices, then "substitute values", or ask around here for help with 'maybe a PSPICE model?? You could always send the manufacturer an email request.) |
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Re: Need help to design a transimpedance amplifier
This is the case when first creating a source of noise, and then heroically fighting with them.
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It is better not to use a charge pump to get negative voltage. You can build tranimpedansny amplifier of three transistors: common collector (npn), Common emitter (npn) and common collector (pnp). Three resistor and feedback resistor. Bordodynov. 04.08.2016, 13:46, "t.obulesu@... [LTspice]" <ltspice@...>: I have uploaded them with the name..New Microsoft PowerPoint Presentation(2).pdf and Noise.pdf here in files.. |
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Re: PWL TRIGGER syntax
Hi.
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Everything works. * D:\Program Files\LTC\LTspiceIV\Draft323.asc V1 x 0 PWL(0 0 1m 1 2m 1 3m 0) TRIGGER V(n003)>1 V2 n003 0 PULSE(0 2 0 10m 10m 0 20m) V3 y 0 TRIGGER V(n003)>1 PWL(0 0 1m 1 2m 1 3m 0) .tran 20m .backanno .end Bordodynov. 04.08.2016, 13:18, "tinix84@... [LTspice]" <ltspice@...>: does somebody have problem with this syntax? PWL (0 0 1m 1 2m 1 3m 0) TRIGGER V(n003)>1 |
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Re: Need help to design a transimpedance amplifier
Am 04 Aug 2016 00:31:30 -0700
schrieb "t.obulesu@... [LTspice]" <LTspice@...>: Let me say why am looking for new design..Hello t.obulesu, this is not the forum to discuss your circuit. Nevertheless, I'm stumbled about the following things, that might give you a hint you could thing about: Interpreting the image tek0000.png (red curve FFT) and in case I'm right, I can see a carrier at about 2.75Mhz with a spectrum of about n times ~300kHz width. This carrier may come from the SPI clock frequency. Furthermore I guess, the 300kHz might come via GND or VCC from the internal DAC oscillators, specified in the range from 250 to 340 kHz in the datasheet. Then, grounded on the fact, that the oscillators of the two DACs are not synchronised, their difference frequency is down-converted and will result as "noise" in the low kHz range. Check your PCB layout with respect to crosstalk paths and GND loops. Sorry for my broken English. -- Mit freundlichen Grü?en Kind Regards Peter Ragosch peter.ragosch@... |
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Re: Need help to design a transimpedance amplifier
Hi.
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The author of this opus (-Building of an optical lever system(1).pdf) or illiterate, or not very neat. Two schemes contain errors. While it may be disinformation. Bordodynov. 04.08.2016, 11:58, "t.obulesu@... [LTspice]" <ltspice@...>: Yahoo! Groups |
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Re: Input impedance of an energy saving fluorescent lamp (CFL) 21W
开云体育To: ltspice@... From: LTspice@... Date: Tue, 2 Aug 2016 20:33:58 +0300 Subject: Re: [LTspice] Input impedance of an energy saving fluorescent lamp (CFL) 21W ?
http://ltwiki.org/?title=Components_Library_and_Circuits
CFL Circuit 13 Watt 120 VAC Compact Fluorescent Bordodynov. 02.08.2016, 19:04, "Jerry Lee Marcel jerryleemarcel@... [LTspice]" : > CFL's are very non-linear, in fact exhibit negative resistance. There are a few Spice models on the internet, you may have to adapt them for LTspice. > > Le 02/08/2016 à 17:42, michael883575@... [LTspice] a écrit?: > >> I am attempting to simulate a loaded inverter using the equivalent input impedance of the CF lamp as the load. Is there anybody in the group who might have an idea as to what a typical value for example for a 21W lamp might be. >> >> Thank you very much in advance >> >> Michael > > ---------------------------------------- > > L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. > www.avast.com > > |
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Re: Input impedance of an energy saving fluorescent lamp (CFL) 21W
开云体育Hi Bordodynov and all who helped, Thank you very much for the link ?and the files for the 13W, 120V AC Compact Fluorescent lamp. Unfortunately, I was looking for a more representative power (20W or nearest and I was hoping to load up to at least 100W/VA) and 230V/240V AC 50Hz . ?I could see how to basically tweek the relevant parameters to achieve what I was looking for but I was not sure that the result would be well and truly representative. ?Besides, I discovered that I had some inherent design flaws in my inverter design which had hitherto been uncovered-- this was not the given model problem. ??After overcoming the inverter problems I found I had in my archives a ballast design from Phillips and some time ago I had written ?a spice based model for a CFL based on a paper published by Shefield University researchers. ?I have now been able to do ?an LTspice simulation for a 30W CFL( I am really looking to simulate the designed inverter output power of 500W/VA) I am still thinking about how to simulate for 500W/VA. ?Ideas most welcome Thanks a lot everbody for your contributions Michael To: ltspice@... From: LTspice@... Date: Tue, 2 Aug 2016 20:33:58 +0300 Subject: Re: [LTspice] Input impedance of an energy saving fluorescent lamp (CFL) 21W ?
http://ltwiki.org/?title=Components_Library_and_Circuits
CFL Circuit 13 Watt 120 VAC Compact Fluorescent Bordodynov. 02.08.2016, 19:04, "Jerry Lee Marcel jerryleemarcel@... [LTspice]" : > CFL's are very non-linear, in fact exhibit negative resistance. There are a few Spice models on the internet, you may have to adapt them for LTspice. > > Le 02/08/2016 à 17:42, michael883575@... [LTspice] a écrit?: > >> I am attempting to simulate a loaded inverter using the equivalent input impedance of the CF lamp as the load. Is there anybody in the group who might have an idea as to what a typical value for example for a 21W lamp might be. >> >> Thank you very much in advance >> >> Michael > > ---------------------------------------- > > L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. > www.avast.com > > |
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Re: Input impedance of an energy saving fluorescent lamp (CFL) 21W
开云体育Hi Bordodynov and all who helped, Thank you very much for the link ?and the files for the 13W, 120V AC Compact Fluorescent lamp. Unfortunately, I was looking for a more representative power (20W or nearest and I was hoping to load up to at least 100W/VA) and 230V/240V AC 50Hz . ?I could see how to basically tweek the relevant parameters to achieve what I was looking for but I was not sure that the result would be well and truly representative. ?Besides, I discovered that I had some inherent design flaws in my inverter design which had hitherto been uncovered-- this was not the given model problem. ??After overcoming the inverter problems I found I had in my archives a ballast design from Phillips and some time ago I had written ?a spice based model for a CFL based on a paper published by Shefield University researchers. ?I have now been able to do ?an LTspice simulation for a 30W CFL( I am really looking to simulate the designed inverter output power of 500W/VA) I am still thinking about how to simulate for 500W/VA. ?Ideas most welcome Thanks a lot everbody for your contributions Michael To: ltspice@... From: LTspice@... Date: Tue, 2 Aug 2016 20:33:58 +0300 Subject: Re: [LTspice] Input impedance of an energy saving fluorescent lamp (CFL) 21W ?
http://ltwiki.org/?title=Components_Library_and_Circuits
CFL Circuit 13 Watt 120 VAC Compact Fluorescent Bordodynov. 02.08.2016, 19:04, "Jerry Lee Marcel jerryleemarcel@... [LTspice]" : > CFL's are very non-linear, in fact exhibit negative resistance. There are a few Spice models on the internet, you may have to adapt them for LTspice. > > Le 02/08/2016 à 17:42, michael883575@... [LTspice] a écrit?: > >> I am attempting to simulate a loaded inverter using the equivalent input impedance of the CF lamp as the load. Is there anybody in the group who might have an idea as to what a typical value for example for a 21W lamp might be. >> >> Thank you very much in advance >> >> Michael > > ---------------------------------------- > > L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. > www.avast.com > > |
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Re: LT1171 model: syncronization not working
To answer the OT question. The VN2222 was a fairly generic ~5 ohm,60V vfet by modern standards. Similar devices are things like the generic? 2N7000 series available from many vendors. So an sot23 substitute device would be an NSD7002A from fairchild or other generic vendors for example. The more modern part will have a much more detailed spec sheet than the supertex part. Taking a quick look at specs they look quite similar. If you know what specs are important to your application, there are likely better choices than the 2n7000 series. Tim |
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