Comments by "SeanBZA" (@SeanBZA) on "Technology Connections" channel.

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  4. The fancy kettle also uses the exact same element as the cheap one, just they use a nice blob of cast aluminium alloy to bond it to the stainless steel plate, and then also put a ring of blue LED's right next to this 150C block of aluminium, to light up the water, so you know it is on. Bets are will the LED dies fail, or the element, but they never last beyond 2 years anyway, with moderate use of once a day for a half kettle of water. Same as the cheap one, made in the same factory, with the same electrical parts. Of course, if you want a no wait solution you can go buy a Zip Hydroboil (does need 230VAC to run it, and you have to have it plumbed in with both water supply and a steam vent pipe, along with the power connection rated for 15A draw) and have up to 19l of boiling hot water right there when you need it, and never fill it up again. Uses a 2.2kW heater element to boil the water, and keeps it just at a slight boil, in an insulated copper tank, and then has a small auxillary tank that has the float and fill valve, that keeps the level in the big tank constant, but also does not fill it fast as used, so it will not ever be below 95C. Thermostat uses the steam, venting into the small tank, to trip off power when the small tank lid hits 60C, so the main tank is always just short of boiling. A few sizes depending on use, from an office with 4 people, to a hotel that does morning coffee and tea to 200 people that all want boiling water over that hour of breakfast. All the parts that fail, tap, element, float, valve, safety switch and thermostat, are spare parts, and easy to change out as well. Just the price is a little more than the $15 kettle at Wallyworld (expensive, the cheap ones here are $10, with a 1 year guarantee, and actually do often outlive it), so be prepared to shell out $847 for the most common 10l model.
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  6. Data in the VBI was generally a SMPTE timecode for the source video, used to display a time counter and frame number for the use of the editor. The other info was close captions, and then you could also have alternate data streams that contained things like title . This came from the original video tape, either Umatic, Betacam or Betacam SP, and was simply transferred to the video stream either by the TV stations or by the duplicator. TV stations would often strip out the SMPTE codes to instead add station control codes, transmit flags ( is this for certain areas only on a national broadcast, or to add local adverts during breaks) and the local transmitter text data, but line 21 would generally be left alone. The Macrovision blocks were generally not going to interfere with the timecode, but the only thing was that the video clamping would be confused by the ramp and would thus result in the decoder not getting a good signal out. Professional VCR units had the ability to turn the video AGC on and off so that you could then record the Macrovision info onto a tape without interference, and also turning it off on playback meant your video was not going to suffer from data corruption during the edit stages as well, though you only put the macrovision on at final dub stage, so that it would have less effect, as it still did cause degradation of the video by not giving as good a vertical lock. Professional VCR units would record macrovision effortlessly, and Panasonic made a lot of semi professional ( Prosumer) VCR units with this available, mostly used for home video editing where you also had generation loss and not having multiple AGC actions lessened the video degradation somewhat. You would have only the camera AGC enabled to handle the initial shooting light variations, then use the edit deck to do your effects, cuts and non linear editing ( you needed an edit deck, and also at least 2 VCR units slaved to it to do the non linear editing before HDD recorders and digital video) and record to the master tape. The edit deck could also do the audio dubbing in linear stereo in a second pass, though HiFi stereo required you to have the audio dub already set up to record. You could get really good results out of that, as good as the best professional edits, as good as VHS could deliver both video and audio wise. just needed a good source video. As to the Teletext and such, pretty much European TV sets, or at least anything that used the Phillips chipset for TV jungle processing had text built in for either free ( for the later chipsets where everything was in one chip and a front microcontroller with an I2C bus connecting them) or with only a small second text processor and a few control bit changes. Siemens also had a set of chips that did this as well, so any of the European TV manufacturers ( Grundig, Phillips, B&O, Normende) and almost all of the old satellite TV decoders as well did both close captioning and text even on the basic sets. The USA had their own chipsets, and most of the European chipsets did out of the box PAL,NTSC in assorted flavours, and SECAM with either no added changes or with only minor changes, but the US ones only did NTSC.
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  18. The tubes shrinking from T12 to T8, and then to T5, was a result of increasing phosphor efficiency. The T12 phosphor was essentially the same phosphor since they were initially developed in the 1920's, and was very limited in operating temperature and allowed light emission. Thus you needed a certain area of phosphor to get a defined light output. Later improved phosphors allowed both higher light output, and higher operation temperature, and also the smaller diameter tubes allowed a reduction of volume of gas fill, and also a drop in the amount of mercury in them, so the mercury went from almost 100mg for a T12 lamp, to 5mg for T8, and down to under 2mg for a T5 tube. CFL units are at around 0.2mg of mercury per lamp typically, ironically making recovery of the mercury near impossible, as it is so little. The biggest killer of them in enclosed and any fixture is that most of the power dissipation is in the filament ends, where you have to heat up the emitter material, so generating all the heat right by the electronics, and also in a nice insulating plastic enclosure. green PCB at manufacture ends up at EOL as being charred black, along with pretty much the entire inside of the lamp. Drawback of LED units is that they are also full of large amounts of toxic metals, Gallium, not so bad but still a heavy metal, and Arsenic, part and parcel of the Gallium Arsenide used to make the light emitting diode chips used in there, plus of course the phosphors are pretty much the same ones used in the flourescent lamps, and those are also a witches brew of heavy metal oxides, enclosing the GaAs chip. Flourescent linear lamps are easy to recycle, mostly glass, a bit of nickel wire, some strontium and tungsten, and a little fill of aluminium and copper from the ends, plus the water soluble phosphor inside, because it is deposited using a water based slurry. Crush up the tubes and wash them, and the wash water has almost all the phosphor and mercury, because it tends to bind with the phosphor (which is why you see so many T5 lamps that are pink, because the tiny amount of mercury in them has been adsorbed onto the phosphor coat strongly), and then you simply use eddy current sorting to pull the metal parts out, and melt them down again, and the glass goes into a furnace to make new ones. CFL units harder to recycle, you have to separate the electronics and the tube, and then mostly just recover the copper and dump the rest, and the same for LED lamps, if recycled only the copper is stripped, all the rest is just more waste to be dumped or buried somewhere. There was a brief period where CFL units had replaceable glass, as the idea was to reuse the electronic unit ballast and have a simple east to replace light emitter, but the integrated CFL quickly killed that as they were cheaper to make. Still have a few of those units around, and they will outlast the LED units very likely, as I also have a good supply of the PL flourescent lamps they use.
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  23. Freezer on the bottom you have a smaller freezer compartment, as it has lost volume to the space for the compressor. As well the insulation there is thinner, to minimise the lost volume, plus it has a lot of hot piping running through thin sections of the insulated wall near the inside, along with 200W of heat from the compressor itself when running. Chest freezers have the luxury of having thicker walls, so there is more insulation, while a fridge freezer upright combination has thinner insulation, and the door also has to have a heater in the inner wall, so that the seal does not freeze onto the case. Larger length of seal area, thus more heat input to keep it not frozen. Seals also lose heat to convection, long vertical strips of airflow allowing heat inside the box, while the chest freezer has almost no convection along the seal in most cases. As well the limiting factor in modern fridge freezer lifetime is not the compressor, those will easily, even for the cheapest ones you find in modern fridges, with cost cutting applied everywhere in manufacture, last 10 years running all the time, provided there are no leaks in the gas system. Sadly that is the killer, the foamed in insulation is done with isocyanate 2 part foam, and as a side effect of the cure they do release acid slightly. This will eventually cause the evaporator pipes, and the condenser pipes, to corrode through from the outside. Most pronounced at the regions of the piping where they are cold enough to condense water from the air in the evaporator, thus at the cold side where the pipe enters, and for the condenser at the hot side, right by the door, where the hot gas is used to keep the seal from freezing in place, and which cools down from heat transfer to the inner side fast when the compressor stops. This then corrodes the steel pipe, used instead of more durable copper, as it is a lot cheaper, and when a small pinhole eventually does corrode through the pipes you are unable to repair it, as the pipes are all buried in the foam, and removal is going to require destruction of either the inner plastic moulding, or the exterior steel skin to expose them, and then you cannot replace the foam easily after replacing the pipes. Look at your modern fridge with a thermal camera and you see where the pipes run, and how haphazardly they are installed before the foam is injected. With refrigerator freezers the fans in the more expensive models also run all the time to circulate the air, and generally fail fast, as they are run in a very harsh environment, with water droplets running through them in the fridge side, and ice in the freezer side. Defrost in the fridge and freezer is done with a heater element by the coils, so that frost is heated up and melted back to liquid, and this then travels down a heated tube to the top of the compressor, where it collects in a pan, and the heat of the compressor evaporates it. Cheap units the heater runs when the compressor does not, but is low power, around 10W to 30W, so does not put much heat in the cavity. When you buy commercial units your efficiency takes a dive though, as convenience in getting stuff in and out, along with having either glass doors with heaters so they do not mist up, or no doors at all, is the driver. However those you can repair, as they are expected to last 20 years or more in service, unlike a domestic unit.
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  28. Funny thing is those are not common by me, the electronic ones, which use a 48V relay, and a resistor to drop the excess voltage, and a diode as rectifier, are common. They use a 12V zener diode to get power for the 555 timer used as control, and, because of ROHS saying no Cadmium containing things, they instead use a photodiode as light sensor. 555 timer drives a transistor or small triac, that shorts out the relay coil, to turn the lamp off. Then you get the more complex ones that the street lights use, where the entire electronics is contained within a IC package, made from clear epoxy, that has the photodiode, amplifier and signal conditioning inside on the small silicon chip, and then this controls a thyristor that operates a 20A relay on the board. Note they also have to withstand all faults, so have a large MOV device across the mains input, 480VAC rated withstand, so that they will still survive and operate even if the nominal 230VAC mains has a fault and goes to 400VAC instead. Residential ones use a 275VAC MOV as protection, the last time there was a phase loss by me that got very unhappy, and blew the cap off the photocell, practically getting it into orbit. Not really going to protect, just clamping voltage to protect the wiring, and trip a breaker as it fails short. Incidentally the street lights, for the most part, come with the photocell socket integrated in, as it is cheaper to make all of them the same, and supply instead a special shorting photocell, which has inside it only a 16A fuse and a 480VAC MOV across the output, so that there is still fuse protection when used in group applications, and the MOV clamps lightning strikes on the line down to a level the ballast and starter, or the LED driver for new ones, will probably survive, and, if not, disconnect the fixture. Most common by me are GE, Siemens and Royce Thompson as photocontrols, with Osram and Phillips (branded as Beka) also having a share, depending really on who won the contract for supply for a particular year. You mostly see Osram or Phillips lamps though, as the most expensive part is the maintenance, and cheap junk lamps fail fast.
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  31. That Galanz fridge will fail in around 5 years, because they use cheap steel pipe for the evaporator and condenser lines, which are taped to the walls inside and outside, before the urethane foam insulation is blown into position to hold it there. This pipe is going to rust through, because of water condensing on the insulation, and wicking into the gap between the pipe and insulation, and then rusting the pipes through. Normally the pipe rusts through near the entry points in the foam, but you cannot replace the pipe without removing the insulation, and it bonds strongly to the plastic and steel. The pipe used is cheap unplated steel pipe, with only a thin coating of varnish on it, because the adding of a zinc plate, to keep it from corroding, would mean they need to have an extra assembly step to sand off the coating at the ends, where they braze it to the fittings for the compressor and drier. Takes an extra 5 minutes on the line, so will not be done, just put the cut ends in place, add the acid based flux, and use an induction heater to heat it up and then apply the braze to it. also you can see they do not remove the flux residue, just a quick spray of paint to attempt to keep it from corroding. Funny thing is the compressor will last easily 20 years, even though it is made with CCA wire, and is filled with mineral oil over any other, as mineral oil will move properly through the system with the R600A refrigerant. Thermostat works on the coil itself, fed through a piece of plastic tube, to be held against the suction line before the compressor. Thus it will only turn off when the cooling is such that the suction to the compressor is coming back at the evaporator temperature, around -10C, and thus saying there is no more heat load there.
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