[LTSPICE] Too many Teravolts!

C

Chris Carlen

Guest
Greetings:

Notice how this circuit causes some major voltage spikes to gazillions
of TV. When the alternate solver is used, no problem.

Also notice that if the entire right half of the circuit containing all
the op-amps is deleted (it is presently not doing anything useful, so
may be deleted) and solved with the default SPICE options, then the TV
spikes don't occur.

Any explanations? Some sort of math routine glitch?



Thanks.


Good day!


The following circuit was originally authored by "Genome":
----------------------------------------------------------------------

Version 4
SHEET 1 2256 1332
WIRE -656 1072 -656 1024
WIRE -656 1200 -656 1152
WIRE -272 576 -272 0
WIRE -272 688 -272 656
WIRE -272 704 -272 688
WIRE -272 1104 -272 832
WIRE -272 1216 -272 1184
WIRE -272 1248 -272 1216
WIRE -112 1072 -144 1072
WIRE -112 1104 -112 1072
WIRE -112 1216 -272 1216
WIRE -112 1216 -112 1184
WIRE -80 1024 -656 1024
WIRE -80 1072 -112 1072
WIRE -32 480 -32 96
WIRE -32 688 -272 688
WIRE -32 688 -32 480
WIRE -32 832 -272 832
WIRE -32 864 -32 832
WIRE -32 976 -32 944
WIRE -32 1008 -32 976
WIRE -32 1216 -112 1216
WIRE -32 1216 -32 1088
WIRE 0 48 -64 48
WIRE 0 96 -32 96
WIRE 0 432 -64 432
WIRE 0 480 -32 480
WIRE 0 832 -32 832
WIRE 48 0 -272 0
WIRE 48 32 48 0
WIRE 48 128 48 112
WIRE 48 240 -64 240
WIRE 48 240 48 128
WIRE 48 272 48 240
WIRE 48 352 48 272
WIRE 48 400 48 352
WIRE 48 416 48 400
WIRE 48 512 48 496
WIRE 48 544 -64 544
WIRE 48 544 48 512
WIRE 48 576 48 544
WIRE 48 688 -32 688
WIRE 48 688 48 656
WIRE 64 976 -32 976
WIRE 64 1056 64 976
WIRE 80 272 48 272
WIRE 80 976 64 976
WIRE 160 0 48 0
WIRE 160 48 160 0
WIRE 160 128 48 128
WIRE 160 128 160 112
WIRE 160 400 48 400
WIRE 160 432 160 400
WIRE 160 512 48 512
WIRE 160 512 160 496
WIRE 192 176 -64 176
WIRE 192 272 160 272
WIRE 192 272 192 176
WIRE 208 976 192 976
WIRE 208 976 208 832
WIRE 224 976 208 976
WIRE 272 352 48 352
WIRE 272 416 272 352
WIRE 272 544 272 496
WIRE 272 688 48 688
WIRE 272 688 272 608
WIRE 288 272 192 272
WIRE 336 176 192 176
WIRE 352 976 336 976
WIRE 352 976 352 896
WIRE 368 976 352 976
WIRE 432 272 368 272
WIRE 448 416 448 352
WIRE 448 544 448 496
WIRE 448 688 272 688
WIRE 448 688 448 608
WIRE 512 832 208 832
WIRE 512 976 480 976
WIRE 576 176 400 176
WIRE 576 272 512 272
WIRE 576 272 576 176
WIRE 592 0 160 0
WIRE 592 48 592 0
WIRE 592 128 592 112
WIRE 592 432 592 400
WIRE 592 512 592 496
WIRE 608 272 576 272
WIRE 640 976 624 976
WIRE 640 1024 640 976
WIRE 656 1024 640 1024
WIRE 656 1056 64 1056
WIRE 720 0 592 0
WIRE 720 32 720 0
WIRE 720 128 592 128
WIRE 720 128 720 112
WIRE 720 240 720 128
WIRE 720 272 688 272
WIRE 720 272 720 240
WIRE 720 352 448 352
WIRE 720 352 720 272
WIRE 720 400 592 400
WIRE 720 400 720 352
WIRE 720 416 720 400
WIRE 720 512 592 512
WIRE 720 512 720 496
WIRE 720 544 720 512
WIRE 720 576 720 544
WIRE 720 688 448 688
WIRE 720 688 720 656
WIRE 784 1040 768 1040
WIRE 800 96 768 96
WIRE 800 480 768 480
WIRE 800 480 800 96
WIRE 800 688 720 688
WIRE 800 688 800 480
WIRE 832 0 720 0
WIRE 832 48 768 48
WIRE 832 176 576 176
WIRE 832 240 720 240
WIRE 832 432 768 432
WIRE 832 544 720 544
WIRE 928 896 352 896
WIRE 928 1008 928 896
WIRE 928 1040 896 1040
WIRE 928 1120 928 1040
WIRE 960 1040 928 1040
WIRE 960 1040 960 864
WIRE 992 832 624 832
WIRE 992 864 960 864
WIRE 992 1008 928 1008
WIRE 992 1040 960 1040
WIRE 1120 0 1088 0
WIRE 1120 176 1088 176
WIRE 1120 432 1088 432
WIRE 1120 544 1088 544
WIRE 1136 848 1104 848
WIRE 1136 1024 1104 1024
WIRE 1136 1120 928 1120
WIRE 1232 0 1200 0
WIRE 1232 80 1232 0
WIRE 1232 176 1200 176
WIRE 1232 176 1232 80
WIRE 1232 320 1232 208
WIRE 1232 352 1232 320
WIRE 1232 432 1200 432
WIRE 1232 512 1232 432
WIRE 1232 544 1200 544
WIRE 1232 576 1232 544
WIRE 1232 688 800 688
WIRE 1232 688 1232 656
WIRE 1264 0 1232 0
WIRE 1264 80 1232 80
WIRE 1264 176 1232 176
WIRE 1264 208 1232 208
WIRE 1264 432 1232 432
WIRE 1264 512 1232 512
WIRE 1264 544 1232 544
WIRE 1376 0 1344 0
WIRE 1376 80 1328 80
WIRE 1376 432 1344 432
WIRE 1376 528 1328 528
WIRE 1376 528 1376 432
WIRE 1408 432 1376 432
WIRE 1472 0 1440 0
WIRE 1472 80 1440 80
WIRE 1472 80 1472 0
WIRE 1472 192 1328 192
WIRE 1472 192 1472 80
WIRE 1504 0 1472 0
WIRE 1712 176 1680 176
WIRE 1712 208 1712 176
WIRE 1712 320 1232 320
WIRE 1712 320 1712 288
WIRE 1728 432 1696 432
WIRE 1728 544 1696 544
WIRE 1744 0 1680 0
WIRE 1744 176 1712 176
WIRE 1840 432 1808 432
WIRE 1840 512 1840 432
WIRE 1840 544 1808 544
WIRE 1840 576 1840 544
WIRE 1840 688 1232 688
WIRE 1840 688 1840 656
WIRE 1856 0 1824 0
WIRE 1856 80 1856 0
WIRE 1856 176 1824 176
WIRE 1856 176 1856 80
WIRE 1856 320 1712 320
WIRE 1856 320 1856 208
WIRE 1872 432 1840 432
WIRE 1872 512 1840 512
WIRE 1872 544 1840 544
WIRE 1888 0 1856 0
WIRE 1888 80 1856 80
WIRE 1888 176 1856 176
WIRE 1888 208 1856 208
WIRE 1984 432 1952 432
WIRE 1984 528 1936 528
WIRE 1984 528 1984 432
WIRE 2000 0 1968 0
WIRE 2000 80 1952 80
WIRE 2016 432 1984 432
WIRE 2096 0 2064 0
WIRE 2096 80 2064 80
WIRE 2096 80 2096 0
WIRE 2096 192 1952 192
WIRE 2096 192 2096 80
WIRE 2128 0 2096 0
FLAG -64 48 PHA
IOPIN -64 48 In
FLAG 832 48 PHB
IOPIN 832 48 In
FLAG -64 432 PHB
IOPIN -64 432 In
FLAG 832 432 PHA
IOPIN 832 432 In
FLAG -272 704 0
FLAG -64 240 PREA
IOPIN -64 240 Out
FLAG 832 240 PREB
IOPIN 832 240 Out
FLAG -64 176 POSTA
IOPIN -64 176 Out
FLAG 832 176 POSTB
IOPIN 832 176 Out
FLAG -64 544 ISNSA
IOPIN -64 544 Out
FLAG 832 544 ISNSB
IOPIN 832 544 Out
FLAG 1136 1120 DEAD
IOPIN 1136 1120 Out
FLAG -144 1072 VTRI
IOPIN -144 1072 Out
FLAG -272 1248 0
FLAG 0 832 +15
IOPIN 0 832 Out
FLAG 1136 848 PHA
IOPIN 1136 848 Out
FLAG 1136 1024 PHB
IOPIN 1136 1024 Out
FLAG 1088 432 ISNSA
IOPIN 1088 432 In
FLAG 1088 544 ISNSB
IOPIN 1088 544 In
FLAG 1408 432 ISNS
IOPIN 1408 432 Out
FLAG 1088 0 ISNS
IOPIN 1088 0 In
FLAG 1504 0 IERR
IOPIN 1504 0 Out
FLAG 1232 352 0
FLAG 832 0 VBUS
IOPIN 832 0 Out
FLAG 1696 432 PREA
IOPIN 1696 432 In
FLAG 1696 544 PREB
IOPIN 1696 544 In
FLAG 2016 432 VFB
IOPIN 2016 432 Out
FLAG 1680 0 VFB
IOPIN 1680 0 In
FLAG 2128 0 IDEM
IOPIN 2128 0 Out
FLAG 1088 176 IDEM
IOPIN 1088 176 In
FLAG 1680 176 VDEM
IOPIN 1680 176 Out
FLAG -656 1200 0
SYMBOL sw 48 128 M180
WINDOW 0 40 65 Left 0
WINDOW 3 38 41 Left 0
SYMATTR InstName S1
SYMATTR Value MSW
SYMBOL sw 720 128 R180
WINDOW 0 72 65 Left 0
WINDOW 3 44 40 Left 0
SYMATTR InstName S2
SYMATTR Value MSW
SYMBOL sw 48 512 M180
WINDOW 0 41 67 Left 0
WINDOW 3 40 43 Left 0
SYMATTR InstName S3
SYMATTR Value MSW
SYMBOL sw 720 512 R180
WINDOW 0 78 68 Left 0
WINDOW 3 51 44 Left 0
SYMATTR InstName S4
SYMATTR Value MSW
SYMBOL ind 592 288 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName LFILTB
SYMATTR Value 25
SYMBOL res 384 256 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName RLOAD
SYMATTR Value 2R5
SYMBOL voltage -272 560 R0
WINDOW 0 37 43 Left 0
WINDOW 3 37 69 Left 0
SYMATTR InstName VBUS
SYMATTR Value 80V
SYMBOL diode 176 112 R180
WINDOW 0 -36 49 Left 0
WINDOW 3 -44 27 Left 0
SYMATTR InstName D1
SYMATTR Value DID
SYMBOL diode 608 112 R180
WINDOW 0 49 49 Left 0
WINDOW 3 39 25 Left 0
SYMATTR InstName D2
SYMATTR Value DID
SYMBOL diode 608 496 R180
WINDOW 0 44 53 Left 0
WINDOW 3 35 30 Left 0
SYMATTR InstName D4
SYMATTR Value DID
SYMBOL diode 176 496 R180
WINDOW 0 -36 50 Left 0
WINDOW 3 -48 29 Left 0
SYMATTR InstName D3
SYMATTR Value DID
SYMBOL res 704 560 R0
WINDOW 0 -62 40 Left 0
WINDOW 3 -64 65 Left 0
SYMATTR InstName R2
SYMATTR Value 0R1
SYMBOL res 32 560 R0
SYMATTR InstName R1
SYMATTR Value 0R1
SYMBOL Digital\\CD4000\\CD4070B 704 976 R0
WINDOW 0 -25 -8 Left 0
WINDOW 3 -27 14 Left 0
SYMATTR InstName U1
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4050B 128 912 R0
SYMATTR InstName U2
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4050B 272 912 R0
SYMATTR InstName U3
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4050B 416 912 R0
SYMATTR InstName U4
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4050B 560 912 R0
SYMATTR InstName U5
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL sw -32 1104 M180
WINDOW 0 -105 141 Left 0
WINDOW 3 -106 115 Left 0
SYMATTR InstName S5
SYMATTR Value COMP
SYMBOL res -48 848 R0
SYMATTR InstName R3
SYMATTR Value 1K
SYMBOL voltage -112 1088 R0
WINDOW 0 -93 58 Left 0
WINDOW 3 -62 181 Left 0
SYMATTR InstName VTRI
SYMATTR Value PULSE(-1 1 0 4u 4u 0 8u)
SYMBOL voltage -272 1088 R0
WINDOW 0 -90 46 Left 0
WINDOW 3 -89 70 Left 0
SYMATTR InstName VDD
SYMATTR Value 15V
SYMBOL Digital\\CD4000\\CD4049B 560 768 R0
SYMATTR InstName U6
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4049B 832 976 R0
SYMATTR InstName U7
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4081B 1040 784 R0
SYMATTR InstName U8
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Digital\\CD4000\\CD4081B 1040 960 R0
SYMATTR InstName U9
SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9
SYMBOL Opamps\\opamp 1296 464 R0
SYMATTR InstName IDIFF
SYMBOL res 1216 416 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R6
SYMATTR Value 10K
SYMBOL res 1360 416 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R7
SYMATTR Value 10K
SYMBOL res 1216 528 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R8
SYMATTR Value 10K
SYMBOL res 1216 560 R0
SYMATTR InstName R9
SYMATTR Value 10K
SYMBOL Opamps\\opamp 1296 128 R0
SYMATTR InstName IERR
SYMBOL res 1216 -16 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R10
SYMATTR Value 10K
SYMBOL res 1360 -16 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R11
SYMATTR Value 15K
SYMBOL cap 1440 -16 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 10n
SYMBOL res 1216 160 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R12
SYMATTR Value 10K
SYMBOL diode 1264 96 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D5
SYMATTR Value ZID
SYMBOL diode 1440 64 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D6
SYMATTR Value ZID
SYMBOL Opamps\\opamp 1904 464 R0
SYMATTR InstName VDIFF
SYMBOL res 1824 416 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R4
SYMATTR Value 1E6
SYMBOL res 1968 416 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R5
SYMATTR Value 10K
SYMBOL res 1824 528 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R13
SYMATTR Value 1E6
SYMBOL res 1824 560 R0
SYMATTR InstName R14
SYMATTR Value 10K
SYMBOL Opamps\\opamp 1920 128 R0
SYMATTR InstName VERR
SYMBOL res 1840 -16 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R15
SYMATTR Value 10K
SYMBOL res 1984 -16 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R16
SYMATTR Value 62K
SYMBOL cap 2064 -16 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 330p
SYMBOL res 1840 160 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R17
SYMATTR Value 10K
SYMBOL voltage 1712 192 R0
WINDOW 0 -101 59 Left 0
WINDOW 3 -101 87 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName VDEM
SYMATTR Value PULSE(0 0.4 0 10n 10n 500u 1m)
SYMBOL diode 1888 96 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D7
SYMATTR Value ZID
SYMBOL diode 2064 64 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D8
SYMATTR Value ZID
SYMBOL voltage -656 1056 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(-1 1 0 200u 10n 0 200u)
SYMBOL res 256 400 R0
SYMATTR InstName R18
SYMATTR Value 1
SYMBOL res 432 400 R0
SYMATTR InstName R19
SYMATTR Value 1
SYMBOL cap 256 544 R0
SYMATTR InstName C3
SYMATTR Value 100p
SYMBOL cap 432 544 R0
SYMATTR InstName C4
SYMATTR Value 100p
SYMBOL ind 64 288 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName LFILTA
SYMATTR Value 25
SYMBOL ind 416 288 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName L1
SYMATTR Value 250
SYMBOL cap 336 192 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName C5
SYMATTR Value 4.7
TEXT -280 744 Left 0 !.MODEL MSW SW(RON=10m ROFF=1E6 VT=5V VH=-2V)
TEXT -280 768 Left 0 !.MODEL DID D(RON=10m)
TEXT 24 1200 Left 0 !.tran 0 1.6m 1u uic
TEXT 24 1176 Left 0 !.include Cd4000.lib
TEXT 24 1128 Left 0 !.MODEL COMP SW(RON=10m ROFF=1E6 VT=0 VH=1m)
TEXT 24 1152 Left 0 !.lib opamp.sub
TEXT -280 792 Left 0 !.MODEL ZID D(RON=10m VREV=2)




--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.
 
----- Original Message -----
From: "Chris Carlen" <crcarleRemoveThis@BOGUSsandia.gov>
Newsgroups: sci.electronics.cad
Sent: Tuesday, April 19, 2005 11:14 PM
Subject: [LTSPICE] Too many Teravolts!


Greetings:
Notice how this circuit causes some major voltage spikes to gazillions of
TV. When the alternate solver is used, no problem.

Also notice that if the entire right half of the circuit containing all
the op-amps is deleted (it is presently not doing anything useful, so may
be deleted) and solved with the default SPICE options, then the TV spikes
don't occur.

Any explanations? Some sort of math routine glitch?
Thanks.
Good day!
Click to expand...
Hello Chris,
I had a hard time with your circuit. I first tried with the
usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry
Lfiltb: 25 Henry
L1: 250 Henry
C5: 4 Farad

What real word circuit contains an ideal 250H coil or
an ideal capacitor with 4 Farad?

Please add the following parasitics by clicking the right
mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7
Lfiltb: Parallel Resistance: 1e7
L1: Parallel Resistance: 1e7
C5: Serial Resistance: 0.01

The simulation will then run with the normal and the
Alternate solver. There are also no more "super spikes".

My learning from this:
Add a little bit loss to circuit elements if they
have such extreme values of ideal inductance and capacitance.
This helps to make it better solveable for any (LT-)SPICE engine.
Your real parts will have decades more loss than I
have added in your example.

Best regards,
Helmut
 
On Fri, 22 Apr 2005 23:31:49 +0200, "Helmut Sennewald"
<helmutsennewald@t-online.de> wrote:

[snip]
Hello Chris,
I had a hard time with your circuit. I first tried with the
usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry
Lfiltb: 25 Henry
L1: 250 Henry
C5: 4 Farad

What real word circuit contains an ideal 250H coil or
an ideal capacitor with 4 Farad?

Please add the following parasitics by clicking the right
mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7
Lfiltb: Parallel Resistance: 1e7
L1: Parallel Resistance: 1e7
C5: Serial Resistance: 0.01

The simulation will then run with the normal and the
Alternate solver. There are also no more "super spikes".

My learning from this:
Add a little bit loss to circuit elements if they
have such extreme values of ideal inductance and capacitance.
This helps to make it better solveable for any (LT-)SPICE engine.
Your real parts will have decades more loss than I
have added in your example.

Best regards,
Helmut
Click to expand...
I thought that fixing inductors was a built-in "feature" of LTspice
that Mikey cited repeatedly as one of the reasons that LTspice is
faster than PSpice?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d4bqgk$m1p$05$1@news.t-online.com...
----- Original Message -----
From: "Chris Carlen" <crcarleRemoveThis@BOGUSsandia.gov
Newsgroups: sci.electronics.cad
Sent: Tuesday, April 19, 2005 11:14 PM
Subject: [LTSPICE] Too many Teravolts!


Greetings:
Notice how this circuit causes some major voltage spikes to gazillions
of
TV. When the alternate solver is used, no problem.

Also notice that if the entire right half of the circuit containing all
the op-amps is deleted (it is presently not doing anything useful, so
may
be deleted) and solved with the default SPICE options, then the TV
spikes
don't occur.

Any explanations? Some sort of math routine glitch?
Thanks.
Good day!

Hello Chris,
I had a hard time with your circuit. I first tried with the
usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry
Lfiltb: 25 Henry
L1: 250 Henry
C5: 4 Farad

What real word circuit contains an ideal 250H coil or
an ideal capacitor with 4 Farad?

Please add the following parasitics by clicking the right
mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7
Lfiltb: Parallel Resistance: 1e7
L1: Parallel Resistance: 1e7
C5: Serial Resistance: 0.01

The simulation will then run with the normal and the
Alternate solver. There are also no more "super spikes".

My learning from this:
Add a little bit loss to circuit elements if they
have such extreme values of ideal inductance and capacitance.
This helps to make it better solveable for any (LT-)SPICE engine.
Your real parts will have decades more loss than I
have added in your example.

Best regards,
Helmut
Click to expand...
Oh..... bum, perhaps you might mention this one to Mike. Mind you it's
probably not his problem but some Windows/News transfer snafu or somesuch.

There have been occasions when pasting text files into newsreaders where
some of the characters go wayward and when things get cut and pasted a bit
more something else happens..... the Greek u seems to be a favourite one.

Values get spumed on.

Yes, I've seen the teravolt/amp thing before, not just in LTspice. And if
I'm interested I start to mess about with series and parallel impedances to
try and tame them.

Spice, not that I know fuck, finds an answer. If the answer satisfies the
question then it is right. Simple as that. Perhaps there is or should be
some way of setting up a box that says 'More than this amps/volts, bugger
off and try again'.

DNA

DNA
 
"Jim Thompson" <thegreatone@example.com> schrieb im Newsbeitrag
news:rnri61p6kbl8ac0p7nt7sbf2q118d096gq@4ax.com...
On Fri, 22 Apr 2005 23:31:49 +0200, "Helmut Sennewald"
helmutsennewald@t-online.de> wrote:

[snip]

Hello Chris,
I had a hard time with your circuit. I first tried with the
usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry
Lfiltb: 25 Henry
L1: 250 Henry
C5: 4 Farad

What real word circuit contains an ideal 250H coil or
an ideal capacitor with 4 Farad?

Please add the following parasitics by clicking the right
mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7
Lfiltb: Parallel Resistance: 1e7
L1: Parallel Resistance: 1e7
C5: Serial Resistance: 0.01

The simulation will then run with the normal and the
Alternate solver. There are also no more "super spikes".

My learning from this:
Add a little bit loss to circuit elements if they
have such extreme values of ideal inductance and capacitance.
This helps to make it better solveable for any (LT-)SPICE engine.
Your real parts will have decades more loss than I
have added in your example.

Best regards,
Helmut


I thought that fixing inductors was a built-in "feature" of LTspice
that Mikey cited repeatedly as one of the reasons that LTspice is
faster than PSpice?
Click to expand...

Hello Jim

Yes there is damping(very small series resistance), but
it is very light. It can be overwritten of course.
Any automatic guess has to be very carefully choosen
so that it doesn't have impact on the the accuracy of
a simulation.

Best regards,
Helmut
 
"Helmut Sennewald" <helmutsennewald@t-online.de> schrieb im Newsbeitrag
news:d4bv7u$gru$00$1@news.t-online.com...
"Jim Thompson" <thegreatone@example.com> schrieb im Newsbeitrag
news:rnri61p6kbl8ac0p7nt7sbf2q118d096gq@4ax.com...
On Fri, 22 Apr 2005 23:31:49 +0200, "Helmut Sennewald"
helmutsennewald@t-online.de> wrote:

[snip]

Hello Chris,
I had a hard time with your circuit. I first tried with the
usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry
Lfiltb: 25 Henry
L1: 250 Henry
C5: 4 Farad

What real word circuit contains an ideal 250H coil or
an ideal capacitor with 4 Farad?

Please add the following parasitics by clicking the right
mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7
Lfiltb: Parallel Resistance: 1e7
L1: Parallel Resistance: 1e7
C5: Serial Resistance: 0.01

The simulation will then run with the normal and the
Alternate solver. There are also no more "super spikes".

My learning from this:
Add a little bit loss to circuit elements if they
have such extreme values of ideal inductance and capacitance.
This helps to make it better solveable for any (LT-)SPICE engine.
Your real parts will have decades more loss than I
have added in your example.

Best regards,
Helmut


I thought that fixing inductors was a built-in "feature" of LTspice
that Mikey cited repeatedly as one of the reasons that LTspice is
faster than PSpice?


Hello Jim

Yes there is damping(very small series resistance), but
Click to expand...
Sorry, it's a very very high parallel resistance.

it is very light. It can be overwritten of course.
Any automatic guess has to be very carefully choosen
so that it doesn't have impact on the the accuracy of
a simulation.

Best regards,
Helmut
Click to expand...
 
Helmut Sennewald wrote:
Hello Chris,
I had a hard time with your circuit. I first tried with the
usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry
Lfiltb: 25 Henry
L1: 250 Henry
C5: 4 Farad

What real word circuit contains an ideal 250H coil or
an ideal capacitor with 4 Farad?
Click to expand...
Thanks for the reply!

Oh, I use 250H coils and 4F caps all the time. The surface mount ones.
Air core inductors and silver mica caps too. ;-)

Seriously, the component values are just bungled by the cut and paste.
This seems to happen a lot. The values should be 25uH, 250uH, 4uF.

Please add the following parasitics by clicking the right
mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7
Lfiltb: Parallel Resistance: 1e7
L1: Parallel Resistance: 1e7
C5: Serial Resistance: 0.01

The simulation will then run with the normal and the
Alternate solver. There are also no more "super spikes".

My learning from this:
Add a little bit loss to circuit elements if they
have such extreme values of ideal inductance and capacitance.
This helps to make it better solveable for any (LT-)SPICE engine.
Click to expand...
Yes.

Good day!


--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.
 
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