NE-2 I-V Curve ??

Well, I'll be interested to see.

Cheers

Phil Hobbs

Doesn't the negative region look EXACTLY like avalanche? Should be the same as breakdown in a junction, right?

Thanks.

You'll just need to learn how to choose the tight solver in LTspice versus the show-off (but poor-convergence) fast one ;-) ...Jim Thompson

It seems to behave like paralleled resistors, each one coming alive in turn as the arc begins. ...Jim Thompson

Or get 100 volts across it without splattering glass on the floor.

That's an NE-2T, the Thompson Bulb, filled with hot air instead of the usual neon mixture.

Definition of conductivity: the motion of charge per second divided by voltage 'gradient' across the terminals. Think in terms of conductivity coming into existance...seems easy enough to model, NOT! Wait! you can use your tanh functions, right?

"Massaging the math". Now that's funny.

It's a lot sharper in a gas.

Cheers

Phil Hobbs

It'll be interesting to see how small a leakage current is enough to help LTspice, anyway. Convergence problems _are_ a huge pain.

Cheers

Phil Hobbs

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.

--sp

John Fields scribbled thus:

As Alan Sugar said many years ago "Stack them high & sell them cheap"...

I already cited that, Notice the curve given in the main article is hand drawn. And that it doesn't say how many bulbs it represents.

And that the article is by Forrest Mims.

Mark L. Fergerson

As Earl Muntz said, "I'll keep cutting out parts, till it stops working!"

I wonder why John Larkin thinks that. He's probably never had to do it.

Mathematicians say "?Give me four parameters, and I can fit an elephant. Give me five, and I can wiggle its trunk". I think the quote goes back to Cauchy, but I can't find a reference. The process of getting the parameters to give you the curve you want can be interesting. For my Ph.D. work I used a non-linear multi-parameter curve fitting program to do the last step of the job.

Do you want it to converge or do you want it to behave like an NE-2?

Both. If you will note in the above thread...

"The post was just my first pass to demonstrate a negative resistance region can be done in a way that doesn't choke any Spice with convergence issues."

Most Spices, LTspice included, throw up on the usual negative resistance modeling.

I think I solved the way to simply input VP, IP and VV, IV (peak and valley numbers) over lunch, on a napkin ;-)

But it'll be a few days before I can write it up into a subcircuit... design review time. ...Jim Thompson

Don't forget to simulate the noise.

Ralph, Every time I see a post by you, I think I should know you from somewhere. Were you ever at Motorola? ...Jim Thompson