Making neons conduct with 0 volts DC

Linear and non linear

Making neons conduct with 0 volts DC

Postby Doug Coulter » Tue Dec 20, 2011 2:16 pm

I can generally count on Joe Sousa to come up with things from left field, either things no one has ever thought of, of that have become arcane and obscure. He's busy, but he sent me some interesting email, reproduced here on some tests he's made recently on simple neon bulbs.

> On Mon, 2011-12-19 at 21:08 -0500, Joe Sousa wrote:
> > Doug, this may be of interest:
> > http://www.radiomuseum.org/forum/rf_tri ... _bulb.html
> > -Joe
/////////////////////////////////////

At 11:50 PM 12/19/2011, Doug Coulter wrote:
Yes, that's really interesting, also interesting because if I understand
> right, the R goes up with voltage...constant current, sort of?
>
> That might be true till the voltage got higher anyway, then you'd have
> the onset of regular discharge I'd guess.
>
> I would also guess that RF frequency had an effect. You might find that
> during parts of the cycle, the thing is turned on hard, but less so
> during zero crossings of the RF current. Duty cycle modulation...
>
> And DC across the bulb should phase shift the effective RF ionization.
>
> However, ion recombination times are on the slow side in a neon bulb, so
> I'd expect to see more effect lower than 1 mhz, from what I've seen in
> plasmas here. To get to the mhz region of interesting effects in plasma
> with a 3" spacing, I'm running 50kv. For neon tubes, the range of
> interest is 60 hz (really 120) gives them time to recombine, but 10's of
> khz not, as they found out with HF ballasts with not-50% duty giving ion
> migration issues.
>
> I'd guess you're coupling some RF into the neon terminals common mode,
> so some circuits would have issues with that.
>
>
> Can I link this on my boards for discussion?
>
> Doug
>
/////////////////////////////////////////

Doug:
Sure, you can link the page for discussion, but I just asked one of the RadioMuseum admins to move the page under the newly created NE-2 tube page. Wait a day or too to see if it moves, or update your link if it dies.

You hit every concept on the head, including the gentle saturation effect where the resistance at 0V is about 2k, while it is about 20k at 30V. It appears that RF-excited neon gets depleted. This is the case with many three-legged amplifying devices.

I attached some measurements I did a few years ago on how long it takes for the trigger voltage to recover it's full value after current to the bulb is turned off. This a deionization profile of sorts. The attached plot suggests that oscillation above 4kHz would be a struggle as only 6V out of the 20V histerisis loop has recovered. The measurements show results for the NE-2 and for the Russian INS-1. On a related topic I attached results for burn-in of the INS-1 bulbs over a week at 1.5mA. This shows how poisoned cathodes can clean up.

Dan Sheingold pointed out the K3-J integrator as using the RF controlled NE-2, so I just took some photos of my unit and uploaded it. The original data-sheet for the K3-J came from scans of your Philbrick material. See http://www.philbrickarchive.org/k3-j_in ... ponent.pdf

-Joe

I'll try to keep up if the link moves. Here's the stuff he sent me directly:
INS-1_NE2_TriggerVoltage_recovery.gif

INS-1_Burnin_1week_at_1500uA.jpeg



I am now wondering what those conduction vs voltage curves over at radiomuseum are really trying to tell us. Space charge, ion collection at one terminal due to DC, what? And wondering how this information might apply to our fusor plasmas. His de-ionization profiles are useful, but we need to remember that they are also gas density and temperature dependent. Neons have a lot more gas in them than a fusor does...
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
User avatar
Doug Coulter
 
Posts: 2934
Joined: Wed Jul 14, 2010 8:05 pm
Location: Floyd county, VA, USA

Re: Making neons conduct with 0 volts DC

Postby David McKee » Wed Mar 26, 2014 10:22 am

This effect could be used to make a neat and simple little lightning detector...
"Mad Science" means never stopping to ask "what's the worst thing that could happen?"
Having too many projects at the same time means never having to say "I'm Bored"...
User avatar
David McKee
 
Posts: 19
Joined: Thu Mar 13, 2014 5:46 pm
Location: Mint Hill, NC

Re: Making neons conduct with 0 volts DC

Postby vmike » Thu Mar 27, 2014 10:47 am

I experimented making lightening and radiation detectors with various neon bulbs several years ago. I biased the bulbs to just below the strike voltage, using them essentially as "miller effect" detectors. Worked.

mike
I tried to contain myself, but I escaped.
User avatar
vmike
 
Posts: 30
Joined: Wed Sep 15, 2010 5:20 pm
Location: Stillwater, Oklahoma

Re: Making neons conduct with 0 volts DC

Postby David McKee » Fri Mar 28, 2014 8:41 am

vmike, that sounds cool - if you got any pics or schematics I would like to seem them! I live in a pretty active lightning area and so this would be a neat little project. (because I don't have enough already! :lol: )
"Mad Science" means never stopping to ask "what's the worst thing that could happen?"
Having too many projects at the same time means never having to say "I'm Bored"...
User avatar
David McKee
 
Posts: 19
Joined: Thu Mar 13, 2014 5:46 pm
Location: Mint Hill, NC


Return to Analog

Who is online

Users browsing this forum: No registered users and 1 guest