Somebody asked for a link to the big power tubes I worked with ...

Looks like a modulator for a big old xmitter.

We chatted about this a while back. I'm a power tube lover. I love the smell of rarefied air around power supplies and tube anodes. I love the fact that you're working with voltages/currents that could instantly kill you. My favorite 'tube' has got to be the mercury rectifier. I forget what island but one island had AC piped in and for some reason built this giant MAR. I don't think this was the railway substation for the Isle of Man although that one built in the 30's is pretty awsome and still in use.

Ummm... that would be the ozone. If you make a habit of ozone sniffing, you may want to check if you're exhibiting any symptoms:

When I worked in 2way radio in Smog Angeles, we would kill or hospitalize at least one technician a year, usually due to high voltage electrocution. My introduction to the statistics was holding a grounded metal case microphone in one hand, while probing around with a long screwdriver in the other hand. That last thing I recall, before the lights went out, was a brilliant purple glow (caused by a combination of parasitic oscillations and a gassy tube) in the final output tube. I later repeated the same mistake several times before I learned my lesson and purchased a better insulated screwdriver.

Hmmm... sounds like a mild case of mercury poisoning.

I haven't had any personal experience with mercury vapor rectifiers. That may help explain why I'm still alive today.

I have an ozone generator + filter. In the right PPM it's beneficial to kill airborne disease. Thanks to that thing I haven't suffered a cold or flu as long as it's been running.

I clipped a wire in an operating voltage tripler with a pair of wire cutters that had a barely visible nick in the insulation. I didn't have a path completed except to the floor wearing regular street shoes but received a fairly nasty burn and shock. I have been shocked into near unconsciousness pulling the guts out of an old photographer's flash supply. Couldn't get it out of the case so I grabbed two un insulated hemostats and clamped on to two places at the same time which unbeknown to me were the outputs of the banks of capacitors that had retained a charge.

the MAR was used extensively in subways and subway cars back before selenium and other SS rectifiers were available. If the power rails were DC the MAR was in the loco. If not it was located at substation(s) located at the main terminal and on the route. MARs were sealed and what mercury was arced during rectification collected on top the glass bulb then dripped back down into the pool at the bottom and the process repeated.

I don't doubt there were on occasions mercury contanminations though.

The mercury vapour rectumfriers that were in the amps, are not quite the same beasts as 'traditional' mercury arc types, although the rectification physics is similar, I believe. The MVRs that were in the Philips amp racks that I referred to, were just like ordinary sized and shaped tubes - KT66ish sort of size, as I recall. I don't think that they were good for too much current, but handled the anode voltage for those 212's just fine. I think that the mercury vapour discharge was self starting.

The ones I always associate with being true MARs, have a big pool of mercury in the bottom, and starter electrodes that dip in it, and arc the vapour out of the mercury to precipitate the main ionisation discharge to the anodes. When these lovely beasts are running, that ignitor electrode (is that the right name for it ? - been a long time since college ) dances about on the top of the mercury pool. Very pretty. The whole bizarre-shaped envelope of the device lights up purple. MARs are good for both high voltage and high current I think.

My first experience of them was at my local cinema when I was a kid. I had a little Saturday morning job 'helping' (!) in the booth. That involved sweeping up and rewinding reels and so on. Both main machines and the big slide projector used for static adverts, employed carbon arc lamp houses, and the DC for them, was fed from a pair of MARs in a big cabinet in the corner of the booth. A bit like an office double door steel cabinet. They fascinated me from the time I first set eyes on them, and I'm sure that they, along with the amplifiers I have been discussing, which I first saw in the window of the small shop where they were originally housed, set me on the path to a career in electronics,

Arfa

There is something mystical/magical about watching a large MAR in action. The largest ever built was in operation until 2004 at the Nelson River Bipole in Manatoba BC. Wish I could find some video of it in operation.

Aye, back in my youth - I grew up on a fairground - I was fascinated by the big mercury rectifiers on some of the rides. I remember the old French guy who had the dodgems was having trouble with fuses blowing, he 'cured' the problem using the showmans method - a six inch nail. The eventual result was that the glass of the rectifier cracked around one of the connections! There was lovely fireworks display inside the bottle.

Ron

And now just wait for lung cancer to hit you.

Ah ok. So ozone causes lung cancer?

I've only seen them in video that I can recall. By the time my interest in electronics sparked it was 1970 and all I had was the blue gaseous glow of 6L6 tubes in Fender amps to marvel at :)

I did however construct a tube rectified voltage tripler from a schematic in a school textbook that put out close to 1kv no load. The textbook was borrowed from a friend who went on to get a college degree in electrical engineering. I have three friends who got those degrees, I chose another path in life and now kick myself in the ass for doing so. However one of these friends got me my first job in the electronics field back in late 70s and I quickly surpassed his technical abilities because of my passion.

We'd best not live by the sea, or anywhere prone to thunderstorms then, Meat, eh ? :-)

Arfa

Ozon is one of the most aggressive gases there is. If any of that reaches your dna inside your lungs, bad things happen. It is no accident that bugs are killed by ozon. And damage is proportional to exposure. The occasional thunderstorm wont harm you. But the air fresheners going 24/7, will.

I don't think there's a cancer link quite yet. However, breathing ozone causes some rather nasty pulmonary irritation:

There are also hints that it has secondary cardiovascular effects:

and DNA damage:

In message , Arfa Daily writes

Not ozone.

Or have a laser printer under your desk..

My mummy never told me it was dangerous breathing in all that ozone, after playing with my electric train set for hours and filling the room with that distinctive arcing and sparking smell.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Ah ! A subscriber to the dimethyl sulphide explanation then ... Well, that's ok. They'll all kill you in the end. Just like anything you eat or drink or do from the moment you wake up, to the moment you go to sleep again (and probably whilst you're asleep as well ... ) d;~}

Arfa

It is also responsible for preventing cosmic rays from burning us alive.

Any? Air is composed of 78 % Nitrogen and 11% Oxygen .05 ppm Ozone and other trace elements of helium, hydrogen, argon and a few others.

Yeah and it's no accident that those bugs killed by ozone are microscopic.

I run my ion generator at 05 ppm. Millions of these air in use today in healthcare facilities and hospitals.

It will if you get struck by a lightning bolt.

I've been running mine for what, 15 years and don't seem to have any brain or lung masses according to a chest and head angiogram of 2008 when a small PE was discovered in my R lung. I know the dangers, have consulted my family physician that I use a purifier and was given a PPM by him not to exceed. Anywhere you have an arc you have ozone. I don't see any bans on arc sources from the FDA.

I do however appreciate your concern. But I am well aware of the concerns.

I guess not. Next time I'm seaside in a costal region known for electrical storms I'll bring my ozone detector and a respirator with an ozone filter..

My DNA is already damaged.

I've noticed. Insanity is hereditary. You get it from your kids.

There seems to be some disagreement as to whether ozone is an oxidizer or antioxidant as well its medical effects:

To the best of my limited knowledge, ozone generators are used in hospitals as sterilizers to kill bacteria, not as some manner of therapy.

Personally, I don't think ozone is a problem except for some oddities I've observed:

1. Anything made of rubber in the area of the ozone generator tends to crumble. Flexible rubber compounds seem to be the most affected (power cords, rubber bands, phone cords, etc). If they don't crumble, they tend to stiffen.
2. The cylindrical generators with the piece of copper wool on top have a substantial electron charge. Electronics in the area sometimes blow up trying to dump all the electrons. I have a customer that insists on using one near his laptop, which has self destructed several times over the years. Same with his mouse, keyboard, and speakers. I can wave an NE-2 neon lamp around his work area and sometimes get it to light up (when the humidity is low).
3. I've seen a slight increase in corrosion in areas around negative ion generators and electrostatic precipitators. S + H2O + O3 -> H2SO4 I'm not sure, but I've had to use contact cleaner on the aforementioned customers video and audio hardware and have had some minor connector issues. It might be my imagination.

Anyway, ozone reacts with organic compounds to produce free radicals, which are generally considered a bad thing. If you find your political position tending towards the radical, you might reduce your ozone concentration.

Meanwhile, go easy on the Jacobs Ladder mad scientist special effects. The spark generates plenty of UV, which breaks down O2 which then recombines to form ozone.

I've sometimes wondered if the popularity of negative ion generators is a plot by the diode and capacitor manufactories to dramatic increase sales. Lots of diodes and cazapitors inside:

Also, don't go near the water:

"A common British folk myth dating back to the Victorian era holds that the smell of the sea is caused by ozone, and that this smell has "bracing" health benefits. Neither of these is true. The characteristic "smell of the sea" is not caused by ozone but by the presence of dimethyl sulfide generated by phytoplankton, and dimethyl sulfide, like ozone, is toxic in high concentrations."