1950s Pifco Sunlamp. Dangerous, obsolete medical therapy curio, based around a carbon arc lamp.
This slightly insane looking device was something used up until the 1960s for a thankfully obsolete type of therapy called Sun ray therapy, which was basically high exposure to UV light, and it was very much a "Cures what ails ya!" type technology, prescribed for everything from stomach ache, chest infections, anemia, mood disorders, all sorts of things.
Instructions might be something like five minutes for your front side, and five minutes for your back side, every night for a week. For example. All while wearing some very Cold War looking UV protective goggles.
Unfortunately, exposure to high levels of UV including dangerous UVC is known and linked to development of skin cancer in older ages, which is why this therapy died off fifty years ago or more.
This device itself is actually remarkably simple. It consists of two carbon electrodes, that are each connected to a screw adjustment, and a nichrome resistance coil (the spring/heating element looking structure below the main electrodes).
To operate it, you apply power, in this case 240V AC from the wall outlet, and then wind the electrodes in until they touch. Winding them apart then allows an electric arc to be drawn out from between the electrodes, giving the characteristic 50Hz buzz of the AC supply.Once lit and the arc has been given a moment to warm up the electrodes, they can be wound further apart. To turn it off, you disconnect the mains power. In this case I have some remote socket adapters that allow me to turn it on and off via remote.
Notice that as soon as the power is switched on, a little red neon indicator illuminates. This is to tell the user that power is on, and despite there being no visible activity, the electrodes are live at 240V and touching them (which is quite possible through that wide guard) would result in a shock.
The coil below which looks very much like a heating element, is called a ballast and it's about the simplest type. What this is for is to limit the power across that arc once it starts striking.
Something like an ordinary filament bulb of the old style, when the filament is cold its resistance is low and it will therefore allow more current to pass, and it will dissipate more power (this is one reason old style bulbs tend to blow, with a very bright flash, on initial switch on). As the filament warms up, its resistance increases, and the current reduces until the whole thing sits at a stable level.
An electric arc doesn't work like that, with an electric arc, as the temperature increases, the resistance across the arc decreases. This means more current would be allowed to flow, which would make the arc hotter still, which would reduce the resistance further, allow more current to flow, making the arc hotter... you see it would be a runaway situation. This is why another source of resistance, needs to be put in.
That's what that ballast does, that essentially sets the power level of the arc.
This device in its basic form, is a carbon arc lamp, the same sort of light source used in very old (19th century) street lighting, WWI and II search lights, cinema projection lamps, studio lights, anything in the old days that basically needed a very intense light source.
For anyone curious this particular example settles down to around 1200 watts after the initial warm up. As can probably be appreciated the heat it gives out is fairly intense.
But yes, don't stand in front of it while it's working, and don't look directly at the arc, because the result will be skin and eye damage. Fun times!
Пікірлер: 7
Nice example, cheers. Do you know what current (Amps.) the lamp drew when arcing, or even the Wattage, I think it was mains voltage (240v). I love old technology and I believe my late uncle made these in a factory called PIFCO on Oldham road, Failsworth, Manchester. UK, I think it was in the 1950's Cheers, John (UK)
@ShokaLion
2 жыл бұрын
That's right this does run directly on mains voltage. I actually didn't know the power draw, so I've just done a few tests, and it turns out when everything's warmed up, the operating current is about 5 amps, so give or take about 1200W when it's running. It will momentarily draw more power on initial start up, because the current limiting ballast is cold, and it will briefly allow more current to flow before it heats up and everything balances out. So on initial spark up you'll see about 1500W but it doesn't take long, no more than ten seconds or so for it to settle down to 1200W. It'll run at this with the electrodes shorted out ("IR Mode" where all that happens is you get a lot of heat off the ballast coil), or when it's arcing, because an open arc like that will draw as much current as it's able to, which in this case is limited by that ballast, so it'll be 1200W either way. Thank you for prompting me to measure this, I've been meaning to for a while!
@happytuber3669
2 жыл бұрын
@@ShokaLion Brilliant my friend, thank you so much for affording me your time.The analysis figures are most helpful and points to me using old cabling which fed a old 8Kwh electric shower. That cabling is on a separate RCB using 10mm twin and earth and is only 4 years old so it's in good nick. Here's to smoking some rods and hopefully not too much RF interference to my neighbours. Cheers, John PS. If the device uses 5 amp at 230v I think Ohms Law put the ballast at 48ohms 😉
@ShokaLion
2 жыл бұрын
@@happytuber3669 Haha indeed! To be honest I only run the thing once in a blue moon, just really as a curio for friends. Exposure to that light for long isn't that great for you after all, plus yeah, I'd probably be causing huge consternation to any ham radio enthusiasts in the immediate area! As to the impedance of the ballast, it'd be interesting to check that with a meter but that wouldn't be trivial I think, at least not to get the working impedance. Cold impedance would be easy - it's right there after all just probe it with a multimeter. But of course you'll get a lower measurement than you'd get when the thing is up to working temperature. Be interesting to directly measure but yeah, good old Ohm's Law pretty much makes it unnecessary. Maybe I'll get the cold measurement just to see out of idle interest. Not tonight though, bit too late to be clattering around with a multimeter at this time of night!
@happytuber3669
2 жыл бұрын
@@ShokaLion Thanks for yet another great reply. The actual impedance of the ballast, using the approximate initial 1500 start wattage draw that you indicated should place it around 38ohms. Thereafter settling to 1200 watts would indicate around 48ohms. (Hopefully, using bog standard Ohms law calculation as you'll appreciate). Please don't go to any extraordinary lengths on my behalf in establishing such values, unless it's for your own interest of course. If you do eventually 'succumb' to that 'need to know' complex we humans possess, I'd welcome the cold ballast resistance for reference. By the time this reply arrives you'll hopefully be in the 'land-of-nod'. 😉🛌🛌
@ShokaLion
2 жыл бұрын
@@happytuber3669 i.imgur.com/tLvcpH2.jpg Ohm's law wins out again, give or take a slight fudge factor to account for corroded connections, and the centre point of the ballast connection having to go through the touching carbon electrodes. Close enough to prove the numbers I'd say though. :)