Saw this old ad posted in Facebook. Now I’m wondering what it was about planes, cars, and razors that bugged people who watched early color tvs and what technology alleviated that concern.
Is that a headphone jack in the bottom right? If so, I’m guessing the common factor all three of those things share is “noise”.
Was there something about the frequency colour TV was transmitted on that was more susceptible to interference?
Yes. I remember watching Saturday morning cartoons and when my Dad used his electric shaver, the picture went all crazy. Visual static is the best way to describe it.
Our neighbours had an old car and when they started it up, similar effect on the picture, even though they were across the street from us.
I am guessing with my experience with TVs back in the day was something to do with the extra circuitry to keep the vertical and horizontal hold in place. Straight line items like razors, or moving items like planes and cars wouldn’t get “jumpy”.
In the 1960s, a bunch of GE color TVs were produced with a misaligned shield over one of its internal vacuum tubes. The result was the TV would emit dangerous levels of X-ray radiation, aimed at a bit of a downward angle. From across the room you were fine, but children sitting directly in front of the TV watching cartoons were pretty much being blasted with unsafe levels of X-ray radiation.
The faulty models were recalled, though as with all recalls quite a few were never returned for repair or replacement. But the recall was widely publicized, and the whole affair led to the Radiation Control Health and Safety Act of 1968. It also set up the myth that color TVs were dangerous (since all of the affected models had been color TVs) and that sitting too close to a color TV was bad for your health. Even though it had only been one manufacturer’s TV and only a few models affected, in the public mind it was all color TVs that were bad.
As for the other bits, having lived close to an airport (intentionally, I worked on airborne radar and flir systems for a defense contractor at the time), I can tell you from experience that airplane radar makes CRT type televisions go all wonky due to RF interference. The electric motors in razors, vacuum cleaners, tools, etc. would also cause a tremendous amount of interference to your TV signal. Cars usually don’t cause interference, but that depends on the ignition system and the type of spark plugs used. Some of them are horrible for RF interference.
They’re talking about electrical interference caused by planes, car engines, and domestic electrical devices that would distort the over-the-air (OTA) signal. I’ll leave it for our resident engineers to explain in detail, but back in those days all sorts of things could cause the incoming broadcast signal to be distorted, especially weak ones from faraway stations.
Although you didn’t have to adjust the tuning of VHF channels the way you did with a radio receiver’s variable potentiometer, you might have to move the antenna around each time you changed channels, and touching the antenna, or even a person moving around the room, might affect the picture. People would tell the person adjusting the antenna, “No… No… Yes! There! Hold it just like that. Now, don’t move. You’ll just have to stay in that position for the rest of the show.”
The really high-tech people had a big antenna on the roof or in the attic on a gizmo that rotated it to face each station’s transmitter when they changed channels.
We eventually had one of those. Where we lived was pretty distant from any tv stations and reception could be poor.
Yep, these were pretty common where I lived. If you used the regular antenna that came with the TV, you were only getting local stations. With a large roof-top or attic antenna, you could pick up all of the Pittsburgh stations about 50 miles away. A lot of folks just aimed the antenna towards Pittsburgh and didn’t bother with a rotor system, but if you wanted to be able to also rotate the antenna towards some of the Ohio stations then you needed a rotor.
Cable television got rid of most of the interference, simply because the TV signals from cable were a lot stronger than OTA signals. But even with cable, my TV still went wonky every time a plane flew over my apartment building.
Modern digital signals are much less susceptible to noise. Unlike analog signals, where noise just adds into the signal, to mess up a digital signal you need enough noise to actually flip bits. Digital TV signals also have error correction so that even if some of the signal does get screwed up, the TV can correct the error. Digital televisions also just freeze-frame if the signal gets too wonky. Your picture may get slow and jittery, but you won’t get noise signals all over the screen like you would with old-fashioned analog televisions.
We didn’t have a color TV but back in those days color TV was in its infancy and probably had more issues. Our house in the 1950s and 60s was about 10 miles (as the crow flies) from an Air Force base. When those planes would fly over the TV picture would begin to shake, rattle and roll, and we’d get lines across the screen when some electric items were used. It was just one of those things people got used to. Some of those issues went away with the advent of cable TV, which gave you solid, steady reception.
That’s an excellent post from a real expert. Thank you. Adding on …
The power output of airborne weather radar has gone down hugely since the 1960s. Much smarter antenna design and vastly more sensitive receivers, as well as changing the frequency band plus computerized signal processing has resulted in vastly more useful radars emitting vastly less energy. And with vastly smaller sidelobes. So less RF sprayed on the ground near airports now versus then. And on frequencies far removed from where analog VHF TV used to be broadcast.
As to cars, back during the Viet Nam war the AC-130s were equipped with a device called the “Black Crow” which was a sensor that detected the RF interference pouring out of the Soviet standard trucks and their RF-noisy ignition systems. It worked well enough that they could detect a blacked out convoy moving in the dark, follow the signal to get into firing position, then plink individual truck aiming at nothing but the RF signature of the ignition.
By the 1960s US passenger cars came equipped with (optional) AM radios and included ignition noise filters so they weren’t jamming their own reception. Of course those components aged & failed, and anyone who didn’t listen to the radio in their car had no idea when the filter(s) had died & they were spraying RF noise all up and down the road wherever they drove. Or the folks who had then-older cars with no such features. The engine started and ran fine whether the filters were in place or not.
Like with the tremendous advances in air pollution control since the 1960s, a lot of engineering has been put into making all our RF emitters of whatever nature play nicely with each other, and also in engineering receivers to be highly specific to what they are listening for and to be real good at rejecting everything else.
So despite vastly more emitters across an ever-widening RF spectrum, somehow it’s not mere impenetrable cacophony out there. Hat’s off to the RF gurus (like yourself) who made / make all this stuff work.
The neighbours’ car I mentioned was an old clunker that their son bought as his first car. Old and probably outdated tech. It was the only car in our neighbourhood that caused the problem.
No doubt the US and most other advanced countries have something similar to The (EMC) Directive 2014/30/EU which “limits electromagnetic emissions from equipment to ensure that, when used as intended, such equipment does not disturb radio and telecommunication, as well as other equipment.”
We had one of those rooftop antennas (all non-cable houses on our street did – our neighbour sold TVs and antennas!). We still got awful interference when my dad used his electric shaver in the 1970s and 1980s. Electric shavers such as my dad’s Philishave (by Philips, = Norelco in the U.S.) weren’t rechargeable like today, they all used wall AC directly (or converted it internally to DC?) to drive their motors.
“…that’ll calm your nerves for good.”
Why does that seem quite threatening.
The US does now, and has had for a long time. But all that became an issue everywhere in the 1950s through 1970s as electromagnetic spectrum pollution became a problem that needed government action to address.
The thread is about the transition era when lots of stuff predated the then-nascent regulations.
Oooh, your town had cable! Luxury!
We had to drive 40 miles to see cable on my Grammie’s tv.
Oooh, thanks! I have wondered about that warning. I remember being told not to sit too close to the TV as a kid.
And I remember the interference caused by other electronic devices, too.
I remember this. My dad asked the family dentist for some X-ray film, which he taped to the corners of the TV screen. He left them there for some time (several days, at least), then had the dentist develop them to see whether they were fogged. They weren’t, so he concluded that our TV was safe.
Even today, cars with spark plugs aren’t allowed at the radio observatory in Green Bank, WV. There are a few old diesel cars and a bunch of bicycles for folks who need to get around the facility.
@Jeff_Lichtman , you don’t need special film for x-rays. It’s just ordinary film with an opaque covering to block out visible light.