Unconnected part LTSpice seems to need (weird ...)

But all I have and take is white pills, calcium & magnesium supplement. Would those work?

:-)

--
Regards, Joerg

http://www.analogconsultants.com/

What if the cracks last more than four hours?

Whoa, there--it isn't so cut and dried. LTSpice has built-in heuristics to prune stuff like that before it runs, but they aren't perfect.

It's a reasonable question why it should work at all, though, and why it silently generates wrong answers without complaining.

ISTM it's a minor bug in the heuristics.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Then she's going to have to finish by herself.

Joerg expounded in news: snipped-for-privacy@mid.individual.net:

That only works for Morpheus.

Warren

I prefer when software tells me before or after it prunes something.

Forrest Gump would have said "It's like a box of chocolates, you never know what you gonna get" :-)

--
Regards, Joerg

http://www.analogconsultants.com/

Some sims will go from running in seconds to running in hours, with minor changes.

I used to run a DOS sim, called ECA, that didn't use the Spice core. It was cool, ran very fast on a 486. It would announce, but cruise right through, warnings of singularities, divide by zero, all that stuff. It just kept going.

John

Interesting, I also grew up with good old ECA224 but that was when the

286 was the latest and greatest. It was quite a useful simulator. Someone told me it merged into EWB but when I tried that at a client I did not like it anymore. For my consulting office I bought MicroSim PSpice. It came with those nice cloth covered IBM-style binders.

I find this sim behavior odd. It seems only naturaly that, in a "what-if" scenario, an engineer disconnects just one leg of a part. After all, that's how we also do it in real life. SPICE is not supposed to "partially smoosh that" and then not tell anyone.

--
Regards, Joerg

http://www.analogconsultants.com/

A lint-equivalent for SPICE netlists would be useful. But since most people seem to use SPICE by poking things until the sim looks nice, it's an experimental science anyway. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs@electrooptical.net
http://electrooptical.net

Mikey is fond of hanging "gmin" on unconnected nodes. I would suspect there's a setting to turn that off, then you get "floating node" errors until you find them all ;-) ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

I'd certainly prefer floating node error messages over guestimating what LTSpice might hang onto a node that is unconnected in the schematic.

--
Regards, Joerg

http://www.analogconsultants.com/

Looking a bit further (I don't use LTspice as my current production tool) it happens that:

• a default 10^-12 gmin option is permanently set. No way to defeat it, apprat from, maybe, setting it to zero.

• look at the log file. The unconnected node is detected.

-- Thanks, Fred.

Thanks, this would explain a lot. That's what Jim suspected, he beat you by 14 minutes :-)

Well, if it can't be turned off I guess I'll have to learn to live with that stuff. No complaints because LTSpice is free and generally doesn't crash. Other SPICEs cost an arm amnd a leg and crash a lot.

--
Regards, Joerg

http://www.analogconsultants.com/

In PSpice each component's pins can be defined as connect with gmin or report error. So maybe it's a component issue? ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

In LTSpice click Tools/Control Panel. Click the Spice tab. Change Gmin as you wish in the upper right box.

John S

Could be dicey. If I set it to zero other things my go kablouie because it's then universal.

--
Regards, Joerg

http://www.analogconsultants.com/

The VALUE of gmin isn't the problem, it's that unconnected pins are being connected to ground (most likely) via gmin. I basically only use LTspice as a viwer and to run netlists, so I don't know the ins-and-outs of configuring pins. Make sure your symbols don't default to connecting thru gmin, rather than balking. ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

topologycheck Num. 1 Set to zero to skip check for floating nodes, loops of voltage sources, and non-physical transformer winding topology Make sure it's set to "1" ...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

Also...

"Mark unconnected pins: Draw a small square at each unconnected pin to flag it as unconnected."

...Jim Thompson

[On the Road, in New York]

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.