On 03/19/2014 10:48 PM, John Larkin wrote:
On Wed, 19 Mar 2014 22:43:18 -0400, Phil Hobbs wrote:

On 3/19/2014 10:40 PM, Jim Thompson wrote:
On Wed, 19 Mar 2014 19:33:10 -0700, John Larkin
wrote:

On Wed, 19 Mar 2014 18:15:21 -0500, John Fields
wrote:

On Wed, 19 Mar 2014 12:41:43 -0700, John Larkin
wrote:

On Wed, 19 Mar 2014 02:03:58 -0500, John Fields
wrote:

On Tue, 18 Mar 2014 10:44:25 -0700, John Larkin
wrote:


If you build the classic neon RC oscillator, it runs very slowly in LT
Spice. If you keep hitting escape, it sort of nudges it along.

---
Perhaps your 'classic' oscillator is different from mine, which
seems to work just fine:

Version 4
SHEET 1 880 680
WIRE -272 208 -320 208
WIRE -160 208 -192 208
WIRE -48 208 -160 208
WIRE 48 208 -48 208
WIRE -48 224 -48 208
WIRE -320 240 -320 208
WIRE -160 240 -160 208
WIRE -320 336 -320 320
WIRE -160 336 -160 304
WIRE -160 336 -320 336
WIRE -48 336 -48 320
WIRE -48 336 -160 336
WIRE -320 384 -320 336
FLAG -320 384 0
FLAG 48 208 OUT
SYMBOL Misc\\neonbulb -48 272 R0
WINDOW 0 40 1 Left 2
SYMATTR InstName NE1
SYMATTR Value2 Vstrike=80 Vhold=60
SYMBOL cap -176 240 R0
SYMATTR InstName C1
SYMATTR Value .1µ
SYMBOL voltage -320 224 R0
WINDOW 123 0 0 Left 2
WINDOW 0 44 56 Left 2
WINDOW 3 31 87 Left 2
SYMATTR SpiceLine Rser=0
SYMATTR InstName V1
SYMATTR Value 150
SYMBOL res -176 192 R90
WINDOW 0 -33 58 VBottom 2
WINDOW 3 -32 58 VTop 2
SYMATTR InstName R1
SYMATTR Value 10meg
TEXT -272 360 Left 2 !.tran 0 10s 0 0.01s uic
TEXT -272 392 Left 2 ;NEON RELAXATION OSCILLATOR
TEXT -272 424 Left 2 ;JOHN FIELDS, 19 MARCH 2014


Hey, plug in Jim's TANH version and see how well that oscillates.

---
We're not talking about Jim's version, we're talking about why you
seem to be having trouble with LTspice native library parts.

Having trouble?

Sometimes LT Spice converges very slowly. It's not the parts so much as it's
Spice itself. Usually you can fiddle with sim params or values to get it to run
faster, but I haven't found a predictable way to do that.

I wish there was a min time step setting, or better yet a fixed time step
setting.

There are in Spice variants you pay for. I think there's a way in
LTspice, also, to set Tstepmax, but I'll leave it up to you to find it
:-}

...Jim Thompson


I really wish you guys would just put a potato in your shorts or
whatever it takes to make you feel confident enough to lay off this crapola.

Hint: put the potato in the front, not the back.

Cheers

Phil Hobbs

I'd like to know how to get LT Spice to quit saying "Stepping source 12
gazillion N-R iterations 165 fill-ins" for minutes at a time, and just get on
with it. Hitting esc a couple of times often works, but it's silly.




ISTR that just makes the plot window catch up with the transient.

There's a list of convergence suggestions at http://tinyurl.com/ox4fkfe
.. It points out that the source stepping mode uses short time steps in
order to make the capacitances dominate the impedance, so that
everything starts up smoothly from zero.

You can set a minimum capacitance from each node to ground

..options cshunt=10f

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

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