NE-2 I-V Curve ??

Oh, ye of little faith...

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

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

It's difficult because neons vary wildly in their behavior. So there is no really good model.

But why make a big deal, and spend a lot of time, to model an NE-2? It's not likely that anybody would care much, and LT Spice has one already.

Feather in one's cap? Where do you get these archaic expressions?

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Missed adding, when I posted my simulation curve: Gas discharge devices don't have hysteresis, except perhaps a very small amount in the ionizing/quenching process (and, of course, temperature), but they _do_ have a negative resistance region... see my other post...

Subject: Re: NE-2 I-V Curve ?? Date: Mon, 17 Mar 2014 16:47:19 -0700 Message-ID:

Sounds like you let LTspice mislead you with its switches-with-hysteresis model?

Looks like there's also some confusion here about TANH curves and TANH-based switch models. TANH-based switch models converge much better, but have absolutely nothing to do with neon gas discharge behavior. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

And it's amazingly, stunningly, stupidly wrong.

We'll maybe not amazingly; we have grown to expect wrong from you.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

--
So say you, but you provide no empirical real-world data which 
supports your claim. 

Instead, you parrot what you hear and proclaim it as truth because 
it passes through your lips.

OK, you win. Who would know more about parrots and feathers than an old hen?

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

This is krw-level criticism. If you don't say where and how it's stupidly wrong, you are being more than a little stupid yourself.

I can't say that I find the first part of the V/I curve - from 0 to 20uA

- to be anything like physically realistic, since there's no low voltage way to get tiny currents through a miniature neon, but this error might make the model more tractable.

Not reliably, and certainly not reliably enough to justify crying "wrong" without being specific about the nature and extent of the error.

--
Bill Sloman, Sydney

just noticed this thread. [plus, Aioe only responds on three groups.]

is the NE-2 the little glass bulb with two electrodes inside, that's put inside those AC mains testors [along with a 100k to 1MEG resistor]?

If so, years ago I characterized a few. Plotted their active region I-V curve. Did I write it down? no, no need to, because I'll remember, right?

From memory, turned on around 90V. Stayed on until 60V, or so.

There was a kind of constant current sink into the discharge. Once the arc fired, the voltage was 'kind of' a constant, plus a rather very small sloped current term ==> very low positive resistance. The arc, once fired seemed to sit near that 'turn off' voltage so as the current shut off, and the arc became 'starved' went like negative resistance and would 'pop' off. Also, from memory, pretty much a 1 Watt device, got hotter than ?? when too much current went through, didn't run them there, so did not explore.

I think I had the luxury of an old Tektronix Curve Tracer, too. Trying to remember the series ON resistance, arrrrggg! vaguely remember in the 10 to

100's ohm range, pretty certain not into the kilohm range, and may not have been linear. Why? could have been the thermal response got included. ...This is too simple. Someone PLEASE go measure!

Sustaining voltages? on the samples I had they were all very close: 60,

61, 62 that kind of range, must have been all from the same lot run. Their lag and capacitance I couldn't get them to self oscillate faster than 20+kHz. Didn't try hard, don't know what is really possible.

So active ON is something like a 60Vdc battery in series with 50 ohms, or such.

Watch out for photons to 'precharge' the gas tube and cause it to fire at lower voltages in your lab lighting versus firing in a dark room. We had those early version of German made 400V gas discharge suppression arc tubes easily pass incoming inspection, yet NOT fire until almost 600 volts in the dark! I think they now do something to 'pretrigger' them so they fire whether in light or dark.

For what it's worth, the best way to power a gas tube [fluorescent bulb] is with a constant power source, not a contant current source, and definitely not a voltage source.

I'll bet Jeff Leibermann has some URLs that actually plot the 'ON' curve of I-V.

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. Right now there are too many coefficients to twiddle to get to a specific curve, so I'm in the process of massaging the math to make it definable with peak and valley parameters, VP, IP and VV, IV. Watch this space. Listen to John "Math and simulation are crutches" Larkin whine like a 6-year-old brat >:-}

Device models you wanted are on the way. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

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

--
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

That was just a first-pass to demonstrate the shape... manipulation/simplification of coefficients underway. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

It's cheating, though, because the slope is so gentle in the low current range. An accurate model might not converge at all well.

See e.g.

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

The slope is not the problem... it's discontinuities, like "IF" statements and switches that give Spice's heartburn. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

There isn't that much difference between the actual I-V behaviour and a switch, though. Smoothing it out by 100 fA worth between zero and 75V won't help modified trap by very much.

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

There is a whole lot of difference. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Well, I'll be interested to see.

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

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

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.