#Technology-Connections #video on 01970 "Numitron" display devices from RCA: seven-segment #displays made of red-hot incandescent filaments in vacuum tubes, basically seven-segment 5-volt lightbulbs, 25mA per filament. He also shows IV-11 VFD tubes, a seven-segment clock he made in college out of LED tape, and a clock he made out of Numitrons, driving them directly from BCD decoder chips without separate driver chips. He catalogs the design errors in the Numitron: the digits don’t lean and so the decimal point makes them off-center; the segments are too thin to be legible; the segments are too far apart (they could have actually crossed in different planes); the vertical segments extend too far; the opaque support board behind the filaments is grey rather than black, reducing contrast and blurring the segments; and the numbers are slightly crooked due to imprecise assembly of the tubes. The Russian clones are even worse.
#video from #Ukraine from three days ago, killing Russian troops with #flying #weaponry. Another “Terra” fundraiser video. This time they’re flying the drones from inside some kind of wooden structure rather than a basement, where they have a butane canister camping stove set up. I think they’re in a trench. Drones with arms made of carbon-fiber tubes again. They’re attacking a similar command-and-control center on the Russian side, in a house with its windows barricaded with sandbags. The first drone, a quadcopter, blows most of the roof off; the second one, a hexcopter, carries a heavier charge, a thermobaric warhead which looks like it weighs close to 5 kg and has tailfins for dropping from a plane. It sets fire to the building. The next drone seems to be carrying an RPG without a fragmentation belt, which they use to attack an IFV (so maybe the armor-piercing HEAT is indeed in play here). They claim the explosion killed all the passengers. The next drone, attacking a squad of three infantrymen on foot, failed to explode on impact, but did explode shortly afterwards, probably killing all three of them with shrapnel. The next drone attacks a lone infantryman, who futilely tries to shoot it down with a rifle. Then they kill another infantryman who was walking slowly because he was wounded. Then they launch another large hexcopter carrying a 3-kg charge to attack a trench; the infantry hear it and flee into the dugout, to no avail. Then there’s another hexcopter with the repurposed thermobaric bomb, which explodes in a trench. They’re apparently driving around Ukraine on the highways in an unarmored van with the door open. #politics
#video about #Argentina president #Milei calling Inácio Lula Da Silva, president of #Brazil, “The perfect dinosaur idiot”, “corrupt”, and “Communist”. Pure talking-head filler, with a voiceover reading tweets.
#video #toread about balls bouncing with backspin from #Mould
#video by #NileRed explaining the Tollens silvering process. His Tollens reagent recipe is 17g silver nitrate (homemade), 2.4g soda lye, and 9mℓ concentrated ammonia: 1ℓ 0.1M AgNO₃, gravity filtration through three or four coffee filters, measure off 150mℓ, add 9mℓ ammonia solution, which with stirring soon complexes away the precipitated silver oxide into the desired diamminesilver complex; then dumps in the 2.4g of lye, and on stirring again the silver oxide precipitated dissolves. Warns of the danger of degradation to silver nitride if not used immediately, which gave some brown discoloration after a few minutes. For the mirror demonstration he shakes this at room temperature for several minutes with 1g dextrose, suggesting that a hot water bath would accelerate it. #materials #bootstrapping