On Wed, 19 Mar 2014 17:22:18 -0500, John Fields
wrote:

On Wed, 19 Mar 2014 11:55:59 -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

Mine's essentially the same except for parts values.

---
How about if you post what you got?

Same circuit, 150 volts, 1 megohm, 10 nF.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

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
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

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

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.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

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

What a setup... Larkin's "potato" is clearly in the back... of his
diaper :-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

On Wed, 19 Mar 2014 19:34:47 -0700, John Larkin
wrote:

On Wed, 19 Mar 2014 17:22:18 -0500, John Fields
wrote:

On Wed, 19 Mar 2014 11:55:59 -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

Mine's essentially the same except for parts values.

---
How about if you post what you got?

Same circuit, 150 volts, 1 megohm, 10 nF.

---
Works fine for me...

On Wed, 19 Mar 2014 19:33:10 -0700, John Larkin
wrote:

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

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?

---
If it isn't doing what you want it to, what would you call it?
---

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.

---
Ask Helmut.

On Wed, 19 Mar 2014 19:48:52 -0700, John Larkin
wrote:


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.

---
Ask Helmut.

On Wed, 19 Mar 2014 19:33:10 -0700, John Larkin
wrote:

[snip]

Sometimes LT Spice converges very slowly. It's not the parts so much as it's
Spice itself.

It usually _is_ the parts, or rather, the model/subcircuit of the
part... discontinuities with no derivatives... the very topic I've
been harping about... making better models.

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.

LTspice runs faster because, by default, the .TRAN command leaves off
filling in the "Maximum Timestep" amount. Thus, on an "active"
circuit with a parasitic oscillation, it skips over that "grass" and
_you_ think your circuit is gorgeous and you chide me when I point out
that it's oscillating, claiming I'm wrong... your standard retort...
when you're wrong, claim the truth is wrong :-(

What you seek is right under your nose...

_Simulate
|
Edit Simulation Cmd
|
Transient
|
[Maximum Timestep]

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

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

On Thu, 20 Mar 2014 06:35:03 -0500, John Fields
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:

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?

---
If it isn't doing what you want it to, what would you call it?

I don't think the library parts have problems. Sometimes Spice converges slowly.
I don't use it often enough that hitting esc now and then is a big deal. When I
esc out of the initial convergence stall, the rest of the sims seem fine.




--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

On Thu, 20 Mar 2014 08:06:04 -0700, Jim Thompson
wrote:

On Wed, 19 Mar 2014 19:33:10 -0700, John Larkin
wrote:

[snip]

Sometimes LT Spice converges very slowly. It's not the parts so much as it's
Spice itself.

It usually _is_ the parts, or rather, the model/subcircuit of the
part... discontinuities with no derivatives... the very topic I've
been harping about... making better models.

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.

LTspice runs faster because, by default, the .TRAN command leaves off
filling in the "Maximum Timestep" amount. Thus, on an "active"
circuit with a parasitic oscillation, it skips over that "grass" and
_you_ think your circuit is gorgeous and you chide me when I point out
that it's oscillating, claiming I'm wrong... your standard retort...
when you're wrong, claim the truth is wrong :-(

What you seek is right under your nose...

_Simulate
|
Edit Simulation Cmd
|
Transient
|
[Maximum Timestep]

...Jim Thompson

Sometimes that helps, often it doesn't. What I really want is a *minimum* time
step. The convergence hangup is almost always at the beginning of a transient
run; once that's over, after a while or after a couple of esc hits, the rest
runs fine.

If the RC neon thing is oscillating at the beginning of the run, it's not real.

It's no big deal; I don't design many neon oscillators.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

On 03/20/2014 11:14 AM, Phil Hobbs wrote:
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.

Ah, I see--it depends on what the solver is doing at the moment.
Usually when mine get hung up it's early in the damped pseudo-transient
stage, where that doesn't help.

A lot of TI's op amp models don't play at all well in LTspice--try the
OPA140, for instance. None of the tricks on the webpage below help that
one at all, whereas it converges instantly with an LM358 macromodel (fwiw).


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

On Thu, 20 Mar 2014 12:01:35 -0400, Phil Hobbs
wrote:

[snip]

A lot of TI's op amp models don't play at all well in LTspice--try the
OPA140, for instance. None of the tricks on the webpage below help that
one at all, whereas it converges instantly with an LM358 macromodel (fwiw).

Easy to see why...

..MODEL S_VSWITCH_1 VSWITCH (RON=1 ROFF=100MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_2 VSWITCH (RON=1 ROFF=100MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_3 VSWITCH (RON=1 ROFF=10MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_4 VSWITCH (RON=1 ROFF=10MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_5 VSWITCH (RON=10M ROFF=100MEG VON=150 VOFF=0)
..MODEL S_VSWITCH_6 VSWITCH (RON=10M ROFF=100MEG VON=150 VOFF=0)
..MODEL S_VSWITCH_7 VSWITCH (RON=1M ROFF=10MEG VON=-10M VOFF=0)
..MODEL S_VSWITCH_8 VSWITCH (RON=1M ROFF=10MEG VON=10M VOFF=0)
..MODEL S_VSWITCH_9 VSWITCH (RON=1 ROFF=10MEG VON=1 VOFF=-1)
..MODEL S_VSWITCH_10 VSWITCH (RON=1 ROFF=10MEG VON=1 VOFF=-1)
..MODEL S_VSWITCH_11 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_12 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_13 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_14 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)

Whoever writes TI's models doesn't know how to apply bounding
conditions except with a switch.... all those switches cause static
convergence problems.

You could substitute Mike's TANH-based switch and see if that helps.

Of course the model works quite well in PSpice in spite of those
switches :-}



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

Often what works around all these obstacles is to have your power
supply be a pulse- or PWL-based source... start up from zero (in a
..TRAN situation) seems to work every time.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

On 03/20/2014 02:12 PM, Jim Thompson wrote:
On Thu, 20 Mar 2014 12:01:35 -0400, Phil Hobbs
wrote:

[snip]

A lot of TI's op amp models don't play at all well in LTspice--try the
OPA140, for instance. None of the tricks on the webpage below help that
one at all, whereas it converges instantly with an LM358 macromodel (fwiw).

Easy to see why...

..MODEL S_VSWITCH_1 VSWITCH (RON=1 ROFF=100MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_2 VSWITCH (RON=1 ROFF=100MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_3 VSWITCH (RON=1 ROFF=10MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_4 VSWITCH (RON=1 ROFF=10MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_5 VSWITCH (RON=10M ROFF=100MEG VON=150 VOFF=0)
..MODEL S_VSWITCH_6 VSWITCH (RON=10M ROFF=100MEG VON=150 VOFF=0)
..MODEL S_VSWITCH_7 VSWITCH (RON=1M ROFF=10MEG VON=-10M VOFF=0)
..MODEL S_VSWITCH_8 VSWITCH (RON=1M ROFF=10MEG VON=10M VOFF=0)
..MODEL S_VSWITCH_9 VSWITCH (RON=1 ROFF=10MEG VON=1 VOFF=-1)
..MODEL S_VSWITCH_10 VSWITCH (RON=1 ROFF=10MEG VON=1 VOFF=-1)
..MODEL S_VSWITCH_11 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_12 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_13 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_14 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)

Whoever writes TI's models doesn't know how to apply bounding
conditions except with a switch.... all those switches cause static
convergence problems.

You could substitute Mike's TANH-based switch and see if that helps.

Of course the model works quite well in PSpice in spite of those
switches :-}



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

Often what works around all these obstacles is to have your power
supply be a pulse- or PWL-based source... start up from zero (in a
..TRAN situation) seems to work every time.

...Jim Thompson


Not with that mess, it doesn't. It toddles along till the power supply
starts to ramp, and then pukes.

The VSWITCH device has a gradual turn-on of some sort as well.

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

On Thu, 20 Mar 2014 14:40:21 -0400, Phil Hobbs
wrote:

On 03/20/2014 02:12 PM, Jim Thompson wrote:
On Thu, 20 Mar 2014 12:01:35 -0400, Phil Hobbs
wrote:

[snip]

A lot of TI's op amp models don't play at all well in LTspice--try the
OPA140, for instance. None of the tricks on the webpage below help that
one at all, whereas it converges instantly with an LM358 macromodel (fwiw).

Easy to see why...

..MODEL S_VSWITCH_1 VSWITCH (RON=1 ROFF=100MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_2 VSWITCH (RON=1 ROFF=100MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_3 VSWITCH (RON=1 ROFF=10MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_4 VSWITCH (RON=1 ROFF=10MEG VON=100M VOFF=-100M)
..MODEL S_VSWITCH_5 VSWITCH (RON=10M ROFF=100MEG VON=150 VOFF=0)
..MODEL S_VSWITCH_6 VSWITCH (RON=10M ROFF=100MEG VON=150 VOFF=0)
..MODEL S_VSWITCH_7 VSWITCH (RON=1M ROFF=10MEG VON=-10M VOFF=0)
..MODEL S_VSWITCH_8 VSWITCH (RON=1M ROFF=10MEG VON=10M VOFF=0)
..MODEL S_VSWITCH_9 VSWITCH (RON=1 ROFF=10MEG VON=1 VOFF=-1)
..MODEL S_VSWITCH_10 VSWITCH (RON=1 ROFF=10MEG VON=1 VOFF=-1)
..MODEL S_VSWITCH_11 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_12 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_13 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)
..MODEL S_VSWITCH_14 VSWITCH (RON=1 ROFF=1G VON=10 VOFF=-10)

Whoever writes TI's models doesn't know how to apply bounding
conditions except with a switch.... all those switches cause static
convergence problems.

You could substitute Mike's TANH-based switch and see if that helps.

Of course the model works quite well in PSpice in spite of those
switches :-}



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

Often what works around all these obstacles is to have your power
supply be a pulse- or PWL-based source... start up from zero (in a
..TRAN situation) seems to work every time.

...Jim Thompson


Not with that mess, it doesn't. It toddles along till the power supply
starts to ramp, and then pukes.

The VSWITCH device has a gradual turn-on of some sort as well.

Cheers

Phil Hobbs

Have you tried forcing a maximum timestep?

Also, I think LTspice supports gmin stepping... which is well worth
trying. (I tend to make gmin stepping my default method.)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.

On Sun, 16 Mar 2014 10:39:38 -0700, Jim Thompson
wrote:

Anyone have an accurate I-V curve for an NE-2 neon indicator lamp?

(I think it's time I applied TANH to it ;-)

...Jim Thompson

Yep. TANH! But handles neon much better if you use
current-controlled voltage source, rather than current-controlled
current source (which will be just ducky for tunnel diode modeling).

Falling back on my math crutches (I use several :-) I show the
preliminary results at...

http://www.analog-innovations.com/SED/NeonModeling_CurrentControlledVoltageSource.pdf

Still need to parameterize the valley shape to suit all possibilities.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)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.