The safety warning about CRTs is no joke. My dad used to work appliance repair in the 80s. These guys were all well trained in that shop. They had a shelf of tvs with dates on them. No tv was to even be looked at until at least 3 days from dropoff, then they discharged the capacitors. They hated the tvs most, because they ran test after test before plugging them back in. I miss the free crap Dad would drag in due to missed payments or abandoned electronics. We had a 24 in industrial microwave that I miss to this day. I could be lazy and microwave anything in that damn thing, regardless of metal content, and could defrost a small turkey.
What do you mean about the metal content in the microwave? Does the larger chamber make it somehow immune to arcing?
Metal is only a problem if it gets near the sides/top/bottom. There are even microwaves that come with a metal rack for the middle that’s suspended by plastic tabs.
Bigger size makes it easier to stay away from the sides.
I was a kid, so don’t remember everything as my Dad explained it, but it used a more powerful magnetron with a pulse system and used a fan to blow the heat. It also cooked hot pockets without leaving the outside cold and lava inside. Moreso than that, I don’t remember as it was a tech geek dad talking to a 12yr old teenager that only cared to listen to the first half. I was a shit, and I regret ignoring the trove of knowledge that man had.
Also, most microwaves won’t do much with silverware as is, this just kinda went a level higher. It was from a restaurant that never paid up, and the shop always sold the leftovers for cost of parts to make up the difference. Our vcrs, vacuums, audio receivers, and other things came from that shop (also scratch and dent from some store I can’t remember the name of, it had a weird shopping procedure. They had display items and cards, and at checkout you handed the cards over and the items were brought down a conveyor belt from the storehouse in the attic. The broken things were sold cheaply in a room in the back)
Edit: looked it up, the name of the store was Service Merchandise
It might have had something that can shift its frequency.
What happens in most microwaves is you get a standing wave. The high and low parts of the wave are always at the same spot. You then get a hot spot at the peak (and trough) of the wave, and a cold spot when the wave is near the zero node.
By shifting the frequency, even just a little, you can shift the hot spots around and more evenly cook the food.
This is obviously more expensive, and these days you can get it in higher end residential microwaves. Way back when, though, it was only something you’d see in industrial models.
If I’m thinking about it correctly then either the standing wave is intentional or the oven is designed badly. You know the wavelength so you can make sure the oven is not an integer multiple of it and the hot spots move around on their own, no fancy frequency shifting required.
It’s not entirely by choice. There’s a limited range of frequencies available.
Thank you for the call out to Service Merchandise. As a kid, that store was awesome.
I saw my first Jaguar system there… and was immediately told I’d never have one because of its expense.
Probably a “strong enough to still heat stuff in a metal bowl” thing.
Taps on top “this bad boy can kill so many Wi-Fi networks”
I repaired TV’s in the 80’s and 90’s. I worked on many of them right after they came in. It was easy to discharge any caps without damaging the units. I respected the potential for getting shocked and the voltage a flyback transformer can produce so I never did get shocked by one.
And then they invented the colour wheel. And the DMD with lots of tiny mirrors. And afterwards they used LEDs and laser diodes…
The micromirror arrays are the wildest of the bunch to me. That is just such a prima facie batshit insane idea and it’s astonishing that it actually works.
“Yeah, we need to be able to individually display and shut off these pixels, so we’re going to go ahead and design a chip with 6,220,800 tiny mirrors that physically tilt when you poke them with electricity. Rather than, I don’t know, literally any other solution that presents itself.”
It sounds insane, but the array that drives it is functionally not that different from the array that individually causes LCD crystals to shift.
I have DLP parts sitting around because they’re cool.
Edit pics:
Edit2 explanation: A white light is focused onto the DLP mirror chip through a kind of kaleidoscopic lens, I’ll spare you the details on that. The individual microscopic mirrors are aligned with charges to bounce light. The mirror array pulses synced frames through the spinning color wheel to create a composite image. It’s a fucking insane idea that barely works… and people like me, with low persistence of vision, are not fooled very well and we see color banding and all kinds of weird artifacting lol
Woah that color wheel… You can see the cyan, magenta, yellow light reflecting but red, green, blue light passing through to the table, respectively. Such a great example of complementary primaries
I’m so happy you noticed, the colors cannot be reproduced in a digital photo, when it shines in the sun it’s so beautiful!
What’s the 4th color on the wheel used for? White minus white… black, yes. But why?
Straight answer, I don’t know lol
Backlit through window
Toplit by LED lamp
There is no way that the pictures I’ve snapped can produce the colors accurately. When I look at that small section, it reflects forest green light back to my eye. The light that passes through seems to be muddy yellowish
Straight answer, I don’t know lol
:)
I tried to find something on the internets. It says something about additional color spaces - in that regard the yellowish color makes sense. and reducing color flickering. 🤷♀️
My assumption was it had something to do with luminosity, but I’m at the end of my technical expertise for this implementation of insane technology lol
There was an idea I read about, sorta along the same crazy track, (might have been Popular Science or something like 25 years ago) where they came up with an idea for a jet that didn’t use traditional control surfaces like ailerons, but rather line the wings and fuselage in thousands of tiny flaps that would all be precisely computer controlled. It would be able to basically mold and shape the airstream around itself to make precise movements.
You are totally remembering correctly! I recall this as well, but the hype died out quickly.
still used for a type of advanced microscopy.
I could also see DLP being applied in new QM research… lasers are being increasingly used to trap and manipulate atomic nuclei
There was a micromirror e-paper too. Though i don’t think they got a reader on market. Got bought up by E Ink corp, like everythiing else e-paper.
So they used to be ridiculously cool, but they’re still ridiculously cool too.
RGB flashing sequentially is the wooooooorst. Most people can’t see it but holy shit i can and it’s like random colored strobes flashing everywhere. Bleh
I believe the crt projector doesnt have that issue
I was referring to the spinning color wheel that op was taking about, but yeah the simultaneous three color projector likely doesn’t have that problem
I’m going to actually you lol
The reason it works better with CRT is because of the phosphors. They continue to glow, long after the signal has passed over. Check out a CRT slow motion.
Everything to do with display technology involves tricking the eye and relying on persistence of vision which is innate.
Yes, I could tell if dlp, whenever my eyes moved.
They fixed the issue by increasing the color changing frequency in led beamers.:)
I still see it in even the most modern projectors, but I’m also able to see the flicker in phones that use pwm dimming which only a very small percent of people can see, so sucks to be me. My eyes seem to work at a much higher image capture rate than most people, which has no apparent benefits, only problems
Useless superpowers… :) CRTs must have been fun.
Interestingly enough crts didn’t seem to cause a problem, my guess is because the pixel phosphors don’t actually flash off, they fade out. But that’s just a guess
Interesting.
It was hard for me to tolerate the 50hz flickering. Especially in peripheral vision. Same with fluorescent tubes. Good times (not).
Oh yeah fluorescent tubes are a awful. They’re not white, they’re sequentially yellow blue yellow blue yellow blue
We had one in an auditorium where I work. Only problem is it was underneath an MRI scanner. Every time they’d open the door to the MRI, the magnetic field would knock the projector tubes out of alignment.
The technician who came out to work on it said it was hopeless. He told us he had a customer whose projector would get out of alignment if he moved a speaker in the room.
I was so happy when we finally replaced it with an LCD projector.
Does anyone remember older 747 jets having these types of projectors to show movies on international flights? Always thought it was so cool.
I used to have one of these. Traded an electric guitar for it, then never set it up, while it sat like a beast in my basement taunting me. As cool as it was, I should’ve never traded that guitar. :(
I remember Center Parcs having one of those things. Lots of fun for overexcited 10 years olds.
2 of them!
