A bit earlier than me, then. Brought up on log tables and slide rules, we were the first to be allowed electronic calculators in maths "O" level (1974).
Ah, but today's lot have no fear. They've been brought up in a sterile, danger-free environment, so they do not recognize danger when it lurks. When I was teaching, students would cheerfully rearrange their circuits with power applied. Although one managed to explode a 741, in general, solid-state electronics doesn't fight back.
In the end, it's all about attitude of mind; you need controlled and informed fear.
The real sting in the tail of the POTS line was arranging for it to ring while someone had it in their mouth.
48V via a few k tickles, 90V @ 20Hz with enough grunt to ring IIRC 6 mechanical telephone bells is on a whole other level of ouch!
Penny ante solid state doesn't fight back, but may I introduce you to the hockey puck IGBT, when fed from a reasonably stiff 600V rail in a motor driver with plenty of bus cap, can and will detonate with a spectacular amount of flying shrapnel when something goes wrong, there are solid state things that warrant a blast shield.
48V via a few k tickles, 90V @ 20Hz with enough grunt to ring IIRC 6 mechanical telephone bells is on a whole other level of ouch!
Penny ante solid state doesn't fight back, but may I introduce you to the hockey puck IGBT, when fed from a reasonably stiff 600V rail in a motor driver with plenty of bus cap, can and will detonate with a spectacular amount of flying shrapnel when something goes wrong, there are solid state things that warrant a blast shield.
No answers on a postcard for this one....this old configuration/ technical design forbidden today as completely unsafe, even in skilled hands. My late 1950´s 405 line B/W TV for universal mains stuck in my fathers loft had an AC input arrangement as per pic. In a car boot sale in Holland one can still pick up these old Bakelite relics,TV´s and radios with case fully insulated except for the antenna terminal at the rear. Absolutely lethal without an isolating transformer, as many continental areas the mains is actually bi-phase !! Hardly surprising apart from no signal available anymore, the fault was the 60uF cap that gone dry.
I remember too that many 1950´60´s large picture TV´s used radioactive coated line o/p tubes . This presented the TV service engineer with many additional hazards. Such was the competition in the ever growing market which ignored the safety hazard.
I wonder if DIY forums did a demographic survey of how many budding oldies are still in the real HV game and the era they started ?
I started in 1959 in an era when it wasn´t unusual for guitar players to get electrocuted. Plastic coated mains wire didn´t exist and conductors mainly rubber coated with woven cotton exterior. Remember, at that time many places had a two wire mains system with the earth connected in the wall socket to the neutral, which was earthed on the distribution board. A lifted or intermittent neutral or earth posed a very dangerous scenario, and yet 70 years on, in some parts of Europe still haven´t been modernized.
I wonder if DIY forums did a demographic survey of how many budding oldies are still in the real HV game and the era they started ?
I started in 1959 in an era when it wasn´t unusual for guitar players to get electrocuted. Plastic coated mains wire didn´t exist and conductors mainly rubber coated with woven cotton exterior. Remember, at that time many places had a two wire mains system with the earth connected in the wall socket to the neutral, which was earthed on the distribution board. A lifted or intermittent neutral or earth posed a very dangerous scenario, and yet 70 years on, in some parts of Europe still haven´t been modernized.
I don't know of any TV signal tubes that had any radioactive elements within or in the glass. I think what you are referring to is the X-Ray scare of the early 1970s in the USA and possibly other countries.
Color CRT's need to have regulated high voltage due the the natural current draw imbalance between the three electron guns. And a 25in tube could have 27kv on the second anode. Early in consumer color TV technology they used a simple shunt regulator consisting of a special triode tube acting like a zener diode. The most popular was the 6BK4. This tube would produce a pencil size stream of X-Rays emanating for the bottom of the chassis. It was harmless unless you put some body part under the TV in that specific location. But public outcry forced this problem to be addressed. The first solution was to use leaded glass on these regulator tubes. Then later they advanced the design to where regulation was accomplished with feedback on the primary side of the horizontal output transformer.
Color CRT's need to have regulated high voltage due the the natural current draw imbalance between the three electron guns. And a 25in tube could have 27kv on the second anode. Early in consumer color TV technology they used a simple shunt regulator consisting of a special triode tube acting like a zener diode. The most popular was the 6BK4. This tube would produce a pencil size stream of X-Rays emanating for the bottom of the chassis. It was harmless unless you put some body part under the TV in that specific location. But public outcry forced this problem to be addressed. The first solution was to use leaded glass on these regulator tubes. Then later they advanced the design to where regulation was accomplished with feedback on the primary side of the horizontal output transformer.
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There was an European manufacturer as I remember the large chassis TV had the sweep tube enclosed in a large screening can with a skull & crossbones imprinted. Somewhere in my dusty notes, for curiosity I will try and find it. Whatever, interesting that the industrial hazards then, one could say were partially accepted at the time. Not now.
Wasn't the antenna connection insulated by means of two small capacitors? That should make it perfectly safe as long as you don't open the enclosure, except that these capacitors were usually paper capacitors that got a way too large capacitance and a large leakage current as soon as some moisture ingressed.
Not on an American color television that had been adapted for PAL operation that I encountered in 1982. It had black and white mains wires and I didn't know which was which. I found out I'd guessed wrong when I plugged the aerial lead in (from a building distribution system, and therefore earthed) and there was an almighty bang. Amazingly, the distribution system survived the experience and the television worked fine once I'd reversed the mains wires.
Yes, it was the high voltages that produced X-rays, not radioactive materials. However, some voltage references included krypton 85 to ensure starting even in total darkness. Worse, some references that must have had radioactive assistance (judged from their data sheet specifications) did not mention the presence of radioactive materials. You wouldn't get away with that now.
Yes the 0xx series of lower voltage gas regulators apparently did contain some Krypton later in their production but I would guess the amount was harmless? Note that your smoke detectors contain Americium 241.
I heard funny stories of new technicians being stumped with aged VR tubes in the dark. Device would work flawlessly on the bench but when the covers were put back on it would fail. Many hours were spent looking for mechanical shorts not knowing this aged VR tube phenomenon!
I heard funny stories of new technicians being stumped with aged VR tubes in the dark. Device would work flawlessly on the bench but when the covers were put back on it would fail. Many hours were spent looking for mechanical shorts not knowing this aged VR tube phenomenon!
Yes, krypton 85 is entirely harmless compared to americium 241. Although smoke detectors used to have an Am241 source, that's been discouraged ever since it was realised that it was a means of buying radioactive waste on the open market. Still, neither have anything on radioactive suppositories that were claimed to increase "vigour" when radioactivity was first discovered, or radioactive toothpaste issued to German soldiers in WWII, and spas with dangerous radon levels are still touted by quacks.
Apparently you did not have a brother that worked in the Steel Mills in the 1960s.
Giant overhead cranes were suspended from rails in the ceiling, they carried large pots full of molten steel.
They ran overhead along the walk paths of the workers.
Accidents did happen.
Giant overhead cranes were suspended from rails in the ceiling, they carried large pots full of molten steel.
They ran overhead along the walk paths of the workers.
Accidents did happen.
A friend worked at an Australian steel mill in mid-80s. He once quietly told me that someone falling into molten steel didn't scream for long. I was so shocked that conversation stopped dead and restarted on an entirely different topic.
The same thing told me my father who had a PhD. in metallurgy and did often gone to the steel factory tours ( as a part of work ).
That actually continued way beyond 1950. Our family's color TV set through the 1970s, a Grundig Color2000TD, a hybrid with 5 tubes, 37 transistors and already 3 Integrated Circuits, still had the live chassis.
Also note that curiosity: a transistor single ended audio output with OT ...
Attachments
American car radios used that very geometry for decades, usually with a TO-3 device on the finless chassis for "heat sinking".
The gentleman was hit by 6KV from a power supply. Its transformer was rated 2.5 amps contimuous.
Be aware there are some ugly burns on the hand. It took a few months to heal, I recall reading in another topic there.
https://amfone.net/Amforum/index.php?topic=44457.0
This man is an experienced engineer and technician and repairs high powered amplifiers and broadcast equipment.
An insulated connector was accidentally touched.
Those connectors are rated 10KV insulation, but something sure wasn't right about it.
(
The link is in an old post on 833 and 3-500Z circuits:
https://www.diyaudio.com/community/threads/833a-and-3-500z-circuits.209097/post-5781674
but should be in the safety discussion, so the link is here too now.
)
Be aware there are some ugly burns on the hand. It took a few months to heal, I recall reading in another topic there.
https://amfone.net/Amforum/index.php?topic=44457.0
This man is an experienced engineer and technician and repairs high powered amplifiers and broadcast equipment.
An insulated connector was accidentally touched.
Those connectors are rated 10KV insulation, but something sure wasn't right about it.
(
The link is in an old post on 833 and 3-500Z circuits:
https://www.diyaudio.com/community/threads/833a-and-3-500z-circuits.209097/post-5781674
but should be in the safety discussion, so the link is here too now.
)