Learning about oscillators in LTSpice

Started by Clifford Heath in sci.electronics.design7 years ago 68 replies

I'm just getting started with LTSpice, and played yesterday with some Colpitts oscillators to my satisfaction. Today I tried a Hartley, and I...

I'm just getting started with LTSpice, and played yesterday with some Colpitts oscillators to my satisfaction. Today I tried a Hartley, and I can't understand some of the behaviour I'm seeing. In the attached circuit, I've added an emitter resister in an attempt to reduce the high collector current. Merely increasing the base resistor didn't help until the oscillator stopped entirely. Act...


LTSpice: Slow on noise sims with foreign opamps

Started by Joerg in sci.electronics.design9 years ago 79 replies

Folks, Yahoo has made the sign-in procedure so onerous (can't get in anymore) that I'll ask here instead of the LTSpice group: I want to do...

Folks, Yahoo has made the sign-in procedure so onerous (can't get in anymore) that I'll ask here instead of the LTSpice group: I want to do some noise simulations, for example with a TI opamp in there. Loading the complete model it spends forever in the stepping phase, then pseudo-damped analysis and whatnot. Is there any way this can be sped up? All I need to see is ballpark where th...


Spice problems

Started by Robert Baer in sci.electronics.design7 years ago 5 replies

Firstly, only the latest LTSpice IV is available,and sources insist only WinXP "or better" will run it. So tried to get old SwitcherCAD...

Firstly, only the latest LTSpice IV is available,and sources insist only WinXP "or better" will run it. So tried to get old SwitcherCAD III; unobtanium. Said, WTF, loaded the LTSpice IV exe, ran it; looks OK - no errors anyway. BUT I have this National Semiconductor Spice file and it barfs on it "Unknown schematic syntax .SUBCKT LM185/27C 99 2" and do not knowhow to fix th...


Sub circuit in Ltspice.

Started by Jamie in sci.electronics.design9 years ago 46 replies

If I create a sub circuit in LTspice, will that circuit's content be exported with the main file or do I need to include that along with...

If I create a sub circuit in LTspice, will that circuit's content be exported with the main file or do I need to include that along with the file? I read the help file but it some what does not give me a fuzzy feeling.. Jamie


Finding LTspice Models

Started by Ricky C in sci.electronics.design2 years ago 13 replies

LTspice is a nice program... well, it's ok in many respects and great in others. But it can be a PITA to find models for. I'm looking at a...

LTspice is a nice program... well, it's ok in many respects and great in others. But it can be a PITA to find models for. I'm looking at a number of possible parts to use in a new design but many of them have no spice models. I'm not so worried about finding an accurate LED model. But I'm using a Schottky diode to prevent back feeding of power through a regulator and I need a


Can you run LTspice on a cellphone?

Started by Steve Wilson in sci.electronics.design5 months ago 35 replies

A google search shows a number of ways of running MS programs on android cellphones. One method suggests running Wine, then you can load...

A google search shows a number of ways of running MS programs on android cellphones. One method suggests running Wine, then you can load whatever EXE desired. Has anyone been able to run LTspice on android? How did you do it, and how well does it work? Thanks, -- The best designs occur in the theta state. - sw


LTspice Tip

Started by Jim Thompson in sci.electronics.design6 years ago 10 replies

As I work my way to a Universal OpAmp Spice Model that you only have to feed the subcircuit 10-12 numbers from the datasheet, I observe that...

As I work my way to a Universal OpAmp Spice Model that you only have to feed the subcircuit 10-12 numbers from the datasheet, I observe that LTspice struggles with what I would consider ordinary hyperbolic functions (bounded, all derivatives exist, are finite, and continuous)... making a straight line out of a transfer curve with soft limiting on each end... and churning... churning... churni...


simple opamp amplifier circuit

Started by panfilero in sci.electronics.design9 years ago 23 replies

I'm simulating on LTSpice, a simple amplifier circuit with a 2.5V offset, but if I don't include a capacitor on my input my output hits the...

I'm simulating on LTSpice, a simple amplifier circuit with a 2.5V offset, but if I don't include a capacitor on my input my output hits the rails... why is this? The link shows what I'm doing in LTSpice thanks http://i555.photobucket.com/albums/jj477/panfilero/Capture-1.jpg


Stepping multiple parameters in a simulation

Started by Jim Thompson in sci.electronics.design8 years ago

A question presented on the LTspice list by John Woodgate prompted my answer, which may be of interest to other...

A question presented on the LTspice list by John Woodgate prompted my answer, which may be of interest to other LTspice/PSpice/whatever users: Here's an extreme example of multi-parameter stepping... In this example "Case" was stepped 1, 2, 3, 4 to get all the combinations needed by the test (IBIS model generation :-


Basic LTSpice question

Started by Aussie in sci.electronics.design5 years ago 22 replies

I'm (very slowly) learning to play with LTSpice. For temperature simulations do the models generally have a temperature dependent...

I'm (very slowly) learning to play with LTSpice. For temperature simulations do the models generally have a temperature dependent characteristics built in? I can do a temp simulation with a Si diode and get some sensible output. With feeding a fixed voltage from a resistor divider into an op amp follower I get no change in the output with temperature. Am I correct in thinking the L...


Interesting Spice Netlisting Quirk

Started by Jim Thompson in sci.electronics.design8 years ago 1 reply

This time I'll try not to hit "Send" before I enter some content :-( In developing Spice models/subcircuits it's useful to include within the...

This time I'll try not to hit "Send" before I enter some content :-( In developing Spice models/subcircuits it's useful to include within the subcircuit declaration the models used. But if you add a line to your development schematic... .MODEL D D It doesn't appear in the netlist, it appears in the .CIR file (this applies to all Berkeley-adhering Spices, but not to LTspice... LTspice...


EL Inverter LTSpice model

Started by bitrex in sci.electronics.design4 years ago 2 replies

I'm curious as to what a good way to model an EL inverter in LTSpice would be, so I can experiment with some dimming circuits without blowing...

I'm curious as to what a good way to model an EL inverter in LTSpice would be, so I can experiment with some dimming circuits without blowing up the bricks on my bench (or taking an unpleasant low-current shock to the fingers by accident. Ouch.) It takes in some voltage between 1-5 volts and spits out around 50-100V RMS, proportional to input and load dependent. It's probably some kind ...


LTSpice high voltage capacitors

Started by bitrex in sci.electronics.design6 years ago 6 replies

LTSpice seems to have a discouraging lack of "high voltage" (> 100V) electrolytic capacitors in its standard library. Is there a third party...

LTSpice seems to have a discouraging lack of "high voltage" (> 100V) electrolytic capacitors in its standard library. Is there a third party library that's good to use? Does it matter much for simulation purposes? Thanks.


Hysteresis for the SW in LTspice question

Started by Maynard A. Philbrook Jr. in sci.electronics.design8 years ago 8 replies

I am trying to emulate a spark gap effect using the SW component in LTspice and the parameter Vh = xxx seems to allude me ! The help...

I am trying to emulate a spark gap effect using the SW component in LTspice and the parameter Vh = xxx seems to allude me ! The help file leaves a lot to be desired and network searches simply point me to the same help file or youtube videos with no sound and very blurry images. Is the value for the hysteresis absolute below the trigger or is an offset from the trigger? ...


LTspice Question

Started by Jim Thompson in sci.electronics.design9 years ago 1 reply

Suppose, in PSpice, I have a behavioral current source that "quits" unless it has at least 0.5V across it... GDC_I1 N_1 N_2 VALUE...

Suppose, in PSpice, I have a behavioral current source that "quits" unless it has at least 0.5V across it... GDC_I1 N_1 N_2 VALUE {(1+TANH(2.2/0.1*(V(N_1,N_2)-0.5)))/2*1mA} Can LTspice understand that line "as is", or must it be changed? If it must be changed, what is the proper syntax? Thanks! ...Jim Thompson -- | James E.Thompson, CTO ...


ltspice temperature label?

Started by frank in sci.electronics.design6 years ago 1 reply

Hi all, maybe it's just me, but I can't figure out how to make ltspice label a trace with the temperature step it corresponds to (or better...

Hi all, maybe it's just me, but I can't figure out how to make ltspice label a trace with the temperature step it corresponds to (or better yet, graph against temperature and not time). Is there any way to make the simulation apply labels (corresponding to the temperature value) on the different traces of a temperature sweep? I hope it makes sense, I'm just counting by hand the different...


A Brief Review of RF Oscillators in LTspice

Started by Steve Wilson in sci.electronics.design3 years ago 11 replies

Some people struggle to try to get an oscillator running in LTspice. This article describes different types of Colpitts and Clap oscillators snd...

Some people struggle to try to get an oscillator running in LTspice. This article describes different types of Colpitts and Clap oscillators snd shows how to calculate the component values to get them to run. Crystal oscillators are discussed, along with a method to drastically shorten the startup and settling time in order to view the actual oscillator waveforms. The descriptions are a...


How do I convert LTSpice netlist/asc to a pcb-lesstif netlist?

Started by Johann Klammer in sci.electronics.design6 years ago 8 replies

I've just found myself hand-copying a circuit from ltspice to gschem again for use with pcb. Is this really necessary or can it be automated?...

I've just found myself hand-copying a circuit from ltspice to gschem again for use with pcb. Is this really necessary or can it be automated? I don't actually need the gschem schematic either... What's the `proper' way to do that? Has anyone got a script or sthg for that? I've found only a tutorial for something called freePCB using LTSpices' PADS export, but that doesn't seem to wor...


LTspice Seminar in Phoenix

Started by Jim Thompson in sci.electronics.design7 years ago 14 replies

I don't know how many lurkers here are in the vicinity of Phoenix, but I will be attending the LTspice Seminar... Tuesday, November 4, 2014...

I don't know how many lurkers here are in the vicinity of Phoenix, but I will be attending the LTspice Seminar... Tuesday, November 4, 2014 8:00 a.m. - 2:00 p.m. Phoenix, AZ Doubletree by Hilton Hotel 2100 S. Priest Drive Tempe, AZ 85282 Tel: 1-480-967-1441) Perhaps some would like to join me after the seminar and tip a few ;-) Register here:


integrated circuit modeling with LTSpice

Started by Michael Robinson in sci.electronics.design10 years ago 14 replies

I'm in the unfortunate position of having to use LTSpice to work on a CMOS circuit design. If you must know why, our school's Cadence...

I'm in the unfortunate position of having to use LTSpice to work on a CMOS circuit design. If you must know why, our school's Cadence installation has bugs. So far I've figured out I can make a level 1 model that successfully shows body effect. I'm working on the parasitics. I can put in a values for Cbd and Cbs; to get Cgs and Cgd I have to put in Cgso Cgdo and specify the gate dime...