On 03/18/2014 11:20 AM, John Larkin wrote:
On Tue, 18 Mar 2014 10:15:27 -0400, Phil Hobbs
wrote:

On 03/17/2014 07:47 PM, Jim Thompson wrote:
On Mon, 17 Mar 2014 12:27:44 -0500, Tim Wescott
wrote:

On Sun, 16 Mar 2014 11:20:38 -0700, Jim Thompson wrote:

On Sun, 16 Mar 2014 13:59:29 -0400, Phil Hobbs
wrote:

On 3/16/2014 1:39 PM, 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


Of course tanh is single-valued, unlike the I-V of a NE2.

Cheers

Phil Hobbs

Unless you are clever, like me :-}

Look back over my piece-wise-linear curve-fitting posts, using TANH,
with all derivatives existing and finite.

In this particular case, as I envision it, there are not even any
break-points involved.

What I seek right now is a reasonably accurate I-V curve.

I can't tell if you're being purposely coy, or if you've missed Phil's
point.

Gas discharge devices like neon lamps have hysteresis: when they're on,
they'll conduct at a lower voltage than their turn-on voltage.

So a simple I-V curve doesn't cut it, unless you're only trying to
simulate the device in the on state, and leaving the user out to dry for
figuring out turn-on and turn-off behavior.

Oh, ye of little faith...


http://www.analog-innovations.com/NeonModeling_1_First_Pass_of_Concept.pdf

A single line equation, 91 characters long, counting every ()*/+- and
alpha-numeric... Algebraic/TANH ;-)

...Jim Thompson


Well, it's got the right number of bumps, anyway, but greatly
overestimates the current in the low-voltage region--that curve should
be in the picoamps or below until the bulb actually strikes. There's no
way you can push 20 uA through an unlit NE2.

Cheers

Phil Hobbs

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.



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

--
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