Spice crazed

Either I've made some silly mistake or LT stands for loony tunes... this sh ould not produce 300v! One I simmed tonight managed 1.3kV apparently!

Version 4 SHEET 1 1136 680 WIRE 816 -112 816 -160 WIRE 592 48 592 16 WIRE 560 64 432 64 WIRE 752 80 752 -64 WIRE 752 80 624 80 WIRE 368 96 112 96 WIRE 560 96 368 96 WIRE 112 112 112 96 WIRE 816 112 816 -16 WIRE 960 112 816 112 WIRE 1104 112 1040 112 WIRE 112 128 112 112 WIRE 368 144 368 96 WIRE 1104 144 1104 112 WIRE 592 160 592 112 WIRE 112 224 112 192 WIRE 432 224 432 64 WIRE 496 224 432 224 WIRE 816 224 816 112 WIRE 816 224 576 224 WIRE 816 240 816 224 WIRE 432 256 432 224 WIRE 752 288 752 80 WIRE 112 320 112 304 WIRE 816 384 816 336 WIRE 112 432 112 400 WIRE 112 448 112 432 WIRE 112 576 112 528 FLAG 112 304 +ve FLAG 592 16 +ve FLAG 112 576 -ve FLAG 592 160 -ve FLAG 112 432 0v FLAG 112 224 0v FLAG 816 -160 +ve FLAG 816 384 -ve FLAG 1104 144 0v FLAG 432 400 0v FLAG 368 224 0v SYMBOL voltage 112 432 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 10 SYMBOL voltage 112 304 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value 10 SYMBOL voltage 112 96 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value SINE(0 0.1 1000) SYMBOL npn 752 -112 R0 SYMATTR InstName Q3 SYMBOL pnp 752 336 M180 SYMATTR InstName Q4 SYMBOL res 1056 96 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 8 SYMBOL Opamps\\LT1001 592 16 R0 SYMATTR InstName U1 SYMBOL res 416 240 R0 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL res 592 208 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 47k SYMBOL cap 416 336 R0 SYMATTR InstName C1

SYMBOL res 352 128 R0 SYMATTR InstName R3 SYMATTR Value 10k TEXT -384 664 Left 2 !.tran .01

NT

Reply to
meow2222
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The 0v node isn't ground! Bizarre.

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John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

What of positive ground systems?

Grant.

Reply to
Grant

If you follow the LTSpice instructions and add global node 0, connecting it to your 0V, everything works.

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-TV
Reply to
Tauno Voipio

s should not produce 300v! One I simmed tonight managed 1.3kV apparently!

Ahhh! Not the first time I've missed that. Thanks everyone

NT

Reply to
meow2222

Why not use the ground symbol?

Type "g"

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John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Sorry if I was unclear. The Add symbol dialog box says 'global node 0' for the ground symbol. The Spice part needs node 0, and it does not care whether the ground is earth or moon or else.

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-TV
Reply to
Tauno Voipio

What seems to be happening in meow's circuit is that 0V is floating, and some ideal current sources inside the opamp are pushing 0V to hundreds of volts against "0" = GND. I've seen that before, pure current sources inside part models, and ground nodes inside parts, both unrealistic. Could be tricky in circuits that run opamps way off ground.

One could devise a test for parts that have sneak currents.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

A node named '0' is _required_ in all netlists. '0V' is not '0' ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Funny, somebody else recently made that same observation.

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John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

It is the 0th Law of Spice.

Reply to
Simon S Aysdie

I just use the ground symbol. It can be invoked with "g" on the KB. Easy and no need to label nets as "0V".

Reply to
John S

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