LT Spice flaws?

We use PADS and use none of the standard library parts. We have our own library, LIB3. We fill out a form to create a new part. That identifies the author and checkers, makes and checks the PADS sch and pcb decals, creates an inventory number, identifies the allowed manufacturers and their part numbers, and tells purchasing to buy some initial stock.

If we revise a part, it gets a new part creation form and a new name in LIB3, like from THING to THING_A, and we usually delete the old one.

Out inventory database names the PADS part for anything in stock and stashes data sheets, links, test data, photos, and notes about any part. Like _BUGGY_OPAMP.txt

We have a class of projects called PROTOS, each with a project number like Z372 or something. That's where we stash any casual PCB layouts, breadboard documentation, test rigs, experimental data, whiteboard scribbles, Spice stuff, pictures of Dremeled things, anything not formally released but worth remembering. We have 317 folders in PROTOS so far.

Our system works pretty well. Somebody could create a similar system to manage an electronics company, with software, and sell it. Or just write a book. I see all sorts of systems and non-systems being used.

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

I've only used LT Spice a few times, but keep going back to MicroCap. I found MicroCap more intuitive. It is also fully featured. You can edit parts and shapes, e.g., tweak the standard schematic symbol. For example, I did not see a symbol for a voltage comparator (the default looks like an op-amp), so I made my own, using the built-in shape editor tool. cheers, Rich S

I use only Trackpoint keyboards. There's no switching back and forth at all. (Plus the Trackpoint was invented by a friend of mine.)

I'd go nuts if I had to use the mouse for everything. I've been using hotkeys since DOS 1.0, nearly 40 years ago, and IIRC I customized my

3270 terminal's key map a couple of years before that. (I was timesharing on UBC's Amdahl 470 V/6 and V/8 running the Michigan Terminal System [MTS]. Pretty cool for the day.)

I still do most of my drawing in Freelance 4.0+ for DOS. Hotkeys galore. Just about all the figures in my book are from Freelance. (Still true in the third edition, coming out some time early next year, God willing.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

It's trivial for LTspice as well. I have a biggish one that I just append models to using a text editor (or even the Linux output redirects). Every nontrivial schematic that's just for my use references it.

s [up comes a text box] .lib \electronics\designs\PHParts.lib

Run simulation. No muss, fuss, or bother.

The "undocumented LTspice" website is useful.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Well, you must be one of those fancy-schmantyz people who learned how to type.

I've discovered (is it new?) that if you, for example, change the name of a mosfet to JLFET or something, and JLFET.mod is in the same folder as the .asc file, it finds JLFET and uses it. That's handy.

new

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What does that mean to "change the name"??? The symbols in LTspice have at tributes. One is called "value" and is the one typically displayed on the schematic, however any or all attributes can be changed.

To point the symbol to a new file requires entering the file name either in the SpiceModel attribute or the ModelFile attribute which can only be acce ssed from the symbol editor, not the schematic editor.

Then there are crazy things like, if you use the SpiceModel attribute to de fine the file name and include a description, the attributes can not be edi ted on the schematic at all. Or some combination like that. I wanted to u se one model file for the TLV333 family of parts (TLV333 single, TLV2333 du al, TLV4333 quad) and just change the displayed name on the symbol. Never found a way to do that. The help file "clearly" explains something that is far to arcane for me to recall right now that means you can't use the attr ibutes in this way.

When using the ModelFile attribute to point to the model file the SpiceMode l attribute is then used to point to the model within the file. The Value attribute is then used as the displayed value on the schematic... or so you would think. The reality is that both the SpiceModel attribute and the Va lue attribute are entered on the command line in the .net file. Insanely e nough the Value attribute is listed first and the SpiceModel attribute is l isted last, both preceded by the parameters. The result is if the Value mo del does not match the SpiceModel the SpiceModel is taken as the model name and the Value is treated as a net name causing an error.

The help file is little use in matters like this. Instead of telling you w hat time it is, the help tells you about the metallurgy required to make th e gears in a variety of timing mechanisms which can potentially be used to keep time.

The support group at groups.io is often helpful, but often not. They seem unwilling to acknowledge any of the limitations of LTspice and the document ation and so are not willing to help in meaningful ways, but are surely wel l intentioned by starting out with a cry of "read the help file" without ev en an indication of which of the hundreds of sections.

One day when I have nothing else to do I might try some experiments to lear n first, what are all the variables that must be controlled. Once that is done, perhaps I have a chance of analyzing the FSM that exists to define th e interface.

Once someone pointed out that a computer is a FSM consisting of potentially 2^N states where N is the number of bits in the CPU and memory. Debugging a program could be defined as determining which of those state bits start in the wrong state.

An LTspice design has a lot of state bits and a very poorly defined state m achine. Do the math.

--

  Rick C. 

  ++ Get 1,000 miles of free Supercharging 
  ++ Tesla referral code - https://ts.la/richard11209

I was a 10-fingered hunt-and-peck typist as a grad student, and decided to force myself to learn touch typing by writing my thesis without looking at the keyboard.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Difficult to touch type on an ASR33; two-fingered hunt-and-peck was all I could manage.

A semblance of touch typing only happened after the cursor and insert/delete keys became available.

But then my first professional program was entered on the hex keypad of Acorn's first product. Fortunately I only had to demonstrate the product principle, because it had to be re-entered every time it was used. Nonetheless it shortened the development time from 6 months to 3 weeks :)