Behavioral voltage source problem

[alec_t]

I wanted to use a behavioural voltage source to simulate a zero-crossing detector, but have run up against a problem: it appears to give up the ghost (in both LTspiceIV and LTspiceXVII) when the dV/dt of the waveform exceeds a quite modest value. Is there a parameter in Control Panel which can be tweaked to get round this?

 

[ericgibbs]

hi alec,
I added 1u step to .tran
Eric
0.1u also works.

 

[alec_t]

Thanks Eric!

 

[eTech]

I wanted to use a behavioural voltage source to simulate a zero-crossing detector, but have run up against a problem: it appears to give up the ghost (in both LTspiceIV and LTspiceXVII) when the dV/dt of the waveform exceeds a quite modest value. Is there a parameter in Control Panel which can be tweaked to get round this?
View attachment 103195

works without modification on my system

 

[ericgibbs]

hi etech,
For ref only, I get the same as alec on my system.
LTSpice IV with Default Settings in Options,, Win XP Pro, 4Gb PC.

E

 

[alec_t]

Interesting. Perhaps the response to the maximum step size setting is processor speed dependent? Wish I was more spice-literate to know what the various settings do .

 

[eTech]

hi etech,
For ref only, I get the same as alec on my system.
LTSpice IV with Default Settings in Options,, Win XP Pro, 4Gb PC.

E

Hmmm...Out of curiosity, I reset all my setting to default (they already were set to default), and reran the simulation.
Still ran ok without modification.

PC- CPU Q6600, SSD, 3Ghz, Win10, LTspiceIV

Also tried this on PC - 4.5Ghz, SSD, Win10, LTspiceXVII. Same result...no errors

 

[ericgibbs]

hi,
Tried 'alecs' asc file in my Toshiba Satellite Pro laptop, Windows 10, LTS IV, same problem.?
E