Highspeed blab of AC powered neon bulb at near and in glow) breakdown voltages - Page 1
Forum section: electronics / general

author: Vtile
author_rank: Super Contributor
timestamp: August 13, 2017, 10:00:25 pm
content: I have been playing with neon bulbs this evening, interesting pieces of technology I must say.Near of the breakthrough voltages happens all sorts of interesting, in 200nA to 5uA region with AC source. With proper biasing it acts as a detector for many sorts of things.It would be interesting to see the AC glow with superduperhighspeed camera.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 14, 2017, 07:06:16 am
content: Yup, 60VDC + (neon) ~= 120V diode with a really weird forward characteristic.Ionization time is in the 10s of microseconds (thus limiting the frequency of a relaxation oscillator to ~100kHz), and light emission isn't very much until it gets well and truly going, so you'd need a truly excellent camera to observe it.It might be easier to observe ionization directly, using laser beams to detect atomic absorption. Most of the laser beam can be nulled by interferometry, making this much more sensitive than direct emission. It might be hard to create a perspective image of this, but I think it would still be possible. (It would be very hard indeed to do with NE-2s, but a chamber could be set up with the same electrodes and fill gas, and better optics.)I doubt it's been done before (unless you can find something in an old physics journal?), but it would make a neat graduate research project at least.Tim

author: Vtile
author_rank: Super Contributor
timestamp: August 14, 2017, 02:32:11 pm
content: I were more in the lines of seeing what 0happens in negative and positive halfcycle change. Also possible some drift (convection) of the glow (plasma?) etc. also it seems it does from a ball of glow between electrodes when you push the neon over the edge with UV -led. While ferro-cerium ash blown from butane lighter seems to put it in over the edge in cracking fashion, I'll think it slightly radio active since why else it would remove electrons from electrodes or from the neon. Even more so since blow of compressed air removes the effect. Dunno, interesting piece of technology, which refuges to die. edit. I assume Dave still have that Cronos? high-speed camera

author: floobydust
author_rank: Super Contributor
timestamp: September 30, 2017, 06:45:28 pm
content: Some neon lamps contain radioactive isotopes, for stabilized firing voltage. Not mentioned on datasheet, other than tight range as I recall.They were used in neon lamp+CDS photo-cell VCA's for compressor/limiters, back to the 1950's.Or maybe it's the gas VR tubes like 0B2 etc.

author: SeanB
author_rank: Super Contributor
timestamp: October 01, 2017, 04:57:04 pm
content: Breakdown can also be influenced by ambient light, and also by external electric fields. Try using a fluorescent lamp starter, they also have the same charactaristics, and also as a bonus have larger electrodes, and are now also radioactive free, making them a lot less likely to strike in darkness till they get hit by a cosmic ray.Quite a few videos about underground lamp assemblies that refuse to strike till you flash a torch to trigger one of them off.