I have a USB hub that I sleep in the same room and its ultrabright boy racer blue LEDs are a nuisance. I can unplug it every night, but that's a nuisance. I've tried taping over the lights but the LEDs are so bright that they kick light out of the USB sockets etc and still manage to make the room glow blue at night.
I don't care about these LEDs and want them gone altogether. Can I open it up and pincer the LEDs, or would that damage the hub? I've had a quick look around on google but don't particularly trust the results.
>>23774 Put several layers of thick, black duct tape. Had this issue as well.
If somehow that doesn't work, a black lacquer could do the job, so get a bottle of finger nail polish at your local goth shop.
>>23774 It's highly likely you can remove them and it wouldn't make a difference to the function of the hub. If by "pincer" you mean crush the plastic part, don't do that - cut them off entirely at the metal leads.
If this was some professional job you could trace the circuit and see how they interact with other components to be sure, perhaps replacing them with regular diodes of a similar rating or adding a current limiting resistor.
But it's a (I'm guessing cheap) USB hub, just fucking do it and buy a new one if you break and can't fix it. Make your technology work for you, don't be a scaredlad like >>23780
Sorry about getting /101/, but seriously, fuck those guys who stick LEDs in everything. They serve no function- an indicator that doesn't shine brightly would be just as effective. Yeah, you can't see it in the dark, but when you want it to be dark you only want to flick one switch, not have to switch loads of things off or have to muck around with tape.
Especially the ones that bloody flash! I've got a external hard drive that looks like a pulsar come nighttime. And why are they all blue? Make a red one or something.
>>23786 >why are they all blue? Make a red one or something
Of all visible LEDs, blue LEDs have to emit the highest frequency light, and were consequently the hardest to manufacture. I'm certain I read about some kind of patent nonsense that had to be resolved in the late 90s which also delayed their emergence on the marketplace, though I forget the details. In any case, it meant that when blue LEDs arrived they were quite a novelty - red and green having been around for several decades. They went from not being available at all to being everywhere in a very short space of time, and quickly became the default choice as an indicator of "newness". This impression of "blue LED = high tech" seems to have perpetuated in the minds of manufacturers.
I had a 4-plug extension lead with a pretty bright LED on it, I just took it apart and cut the LED wire with scissors. It worked so well that I did it with a second one shortly afterwards.
>>23786 It's all to do with the materials. You need different semiconductors for different wavelength light, so if the materials to make blue LEDs are cheapest that's what everyone will use
>>23794 Nah, I think >>23791 is more on the ball, to be honest. The price of an LED doesn't differ that much nowadays, but red, yellow and green ones have been about for fucking yonks and the lifetime of elusiveness of the blue LED and its eventual development actually leading to the awarding of a Nobel prize does as a bit of prestige to them.
It's part of a broader, often subconscious set of perceptions about a product based on the industrial design.
Originally, radios and TVs were built into wood housings. Plastic took over quite quickly, but the use of wood veneer was common for decades because it looked "normal" and carried connotations of quality. The use of wood veneer carried over to early video recorders and games consoles, to make them look like a normal part of the living room rather than a newfangled gadget. As people embraced technology, manufacturers stopped using the wood veneer disguise and embraced a more diverse range of styling. Today, a lot of studio recording equipment is built with wooden end-cheeks when the manufacturer wants to imply that the equipment has a "warm, vintage character".
Early PCs were usually beige, because they were a piece of office equipment. They chose the same bland colour used on typewriters and filing cabinets, so that computers would fit unobtrusively into an office environment. At the turn of the millenium, PC gamers started respraying their computers and modding them with windows and fluorescent lights, which specialist manufacturers eventually imitated; Simultaneously, Apple launched the iMac in a range of vibrant translucent colours. Eventually, beige stopped being merely the default colour and became symbolic of bland and underpowered corporate IT; Major manufacturers switched to black, because it was still relatively neutral but avoided the growing stigma of beige equipment.
As mentioned previously, blue LEDs came to market later than other colours and were initially much more expensive. Blue LEDs were something of an extravagance, and implied that cost-cutting was not a factor in the product design. As the price of blue LEDs fell, they were used more widely to take advantage of this cachet, eventually becoming the norm. Now we have a contrary trend, where manufacturers are abandoning blue LEDs to differentiate their products, and blue LEDs are starting to signify cheap mass-market products with obsolete or thoughtless design.
>>23804 This might be utter bullshit, but I seem to remember hearing that no cellular phone has ever actually needed an aerial but for years and years manafacturers put one on because they believed people wouldn't use them without one.
I considered fact checking this, but I feel I should give someone the chance to shout down my half remembered factoid.
>>23817 That depends on what you mean. As radio devices, they certainly need an antenna, but it doesn't need to be a sticky out thingy on the side of the case as they used to be but can be hidden inside - in the case of one iPhone, part of the metal lining of the case itself was an antenna, which is why it was vulnerable to the "death grip" thing.
>>23821 I'm told that they were needed (or helped greatly) for FM signals, but that the vehicle body itself does quite nicely for AM. Fair warning that like any information conveyed via the internet it may be completely wrong.
Purely anecdotal, but when the aerial for my mum's old car came off the radio was borked for most regional stations. If I'd known I'd have torn it off myself.
AM broadcast wavelengths are so immense that a typical whip antenna is basically useless. Radio 4's longwave frequency of 198kHz equates to about 1500 metres; The corresponding FM frequency of ~93mHz equates to just three metres. For FM, it's easy to build a half or quarter wavelength whip or helical, but that would be completely impractical for AM. The typical antenna for MW/LW is a ferrite rod with a huge number of wraps of thin enamelled wire. These antennae are woefully inefficient, but they're the only practical way of receiving such low frequencies using a compact antenna. The car body isn't used as an antenna, but as a ground plane.
These days most manufacturers have abandoned the traditional FM whip antenna for aerodynamic reasons. Instead, the antennae for the various receivers (AM, FM, DAB, GPS) are hidden in a little "shark fin" on the roof.
>>23826 If it is within the < 20 kHz range you can use a sound card to do most of the work. Lower than that and you might be struggling a bit. Are you trying to find the brown note?
You can receive VLF and ELF signals quite easily, using nothing more than the sound card on your PC and a big drum of wire. These bands aren't used much for transmissions because of the very limited bandwidth available, so most of what you'll receive will be atmospherics and a few timing pulses. Some amateurs are operating experimentally in the VLF bands using QRSS. Bear in mind that the length of a 5kHz radio wave is 60 kilometres, so things get pretty bloody weird down at those frequencies. Almost any electrical device will cause local VLF interference to some degree.
Transmitting legally below 9kHz will require a full amateur radio license with a Notice of Variation for a Special Research Permit. If you're not already a licensed radio amateur, you'll need to take three exams and apply to Ofcom. I would highly recommend taking your exams if you're interested in radio, because getting your license opens up a whole world of opportunities and the process of studying is very informative. Many amateur radio clubs offer very inexpensive weekend courses for the Foundation license.
It is essentially impossible to triangulate VLF signals, so I doubt you'd get caught if you were operating without a license; However, anyone with the technical skill to build and operate a VLF transmitter should easily be able to pass the full set of amateur radio exams.
If you're just interested in tinkering with radio, then the ISM bands are open to everyone, providing you abide by the limits on effective radiated power. You can buy inexpensive Tx/Rx modules for many of these bands, including Arduino-compatible modules.
There is a great deal of interesting stuff happening up in the HF bands (3MHz to 30MHz/100m to 10m). These are the bands that really excite most amateur radio operators, because the frequencies are low enough to propagate worldwide, but there's enough bandwidth for all sorts of transmission modes - voice, morse, data and more. With an HF receiver and a basic antenna, you can pick up everything from North Korean propaganda to Russian spy transmissions to Japanese shipping. You can buy a Software Defined Radio receiver on eBay for about £40 that has useful receive coverage from 100kHz to 1.7GHz with the right antenna, or you can listen in on the HF band via a web-enabled SDR receiver.
I like stochastic models, you can resolve a surprising amount of information from what at first appears to look just like noise. Monte carlo is wonderful.
I'd never heard of magnetotellurics, but I am thoroughly impressed. Petroleum geology is light-years ahead of other industries in so many fields. The EM sources mentioned in the papers I've read are easily amongst the most powerful mobile sources ever built. In spite of chucking biblical amounts of energy at the problem, they're still sifting out unbelievably puny return signals from the noise floor.
Generally speaking stacking the phase shift waveforms in both time and frequency domains is the way to go. I guess any general filtering processing focussed around the specific design of the apparatus helps a bit as well, just a standard bandpass filter or something would chop out a fair chunk of noise. Beyond that, as I said, a series of stochastic models helps i.e. repeatedly wack random numbers into your model then discount results which dont make sense or are at the extreme end of the gaussian distribution.
Bumping mainly because this was a good thread. Thanks to everyone who took part, er, two years ago.
>Honestly though, if I were you, I wouldn't muck about.
>Make your technology work for you, don't be a scaredlad like >>23780 Unfortunately, though, the former was correct; my hub died shortly after I killed the LEDs.
I am about to do the same again, so apparently I haven't learned my lesson. Fuck blue LEDs, eh.
I can't remember which of those I posted.
It's hard to believe that cutting the LED legs hurt anything, though. Even the crappiest design shouldn't be relying on the LED current to drag the supply voltage down - and if the hub was powered from either the input cable or a proper external power supply, then if that killed it, it was a mercy killing.
Do it again, fuck blue LEDs.
(Blue is starting to fall out of favour in stuff I'm designing. Partly fashion, and partly because I just don't have enough voltage to run the damn things. Products that run off a pair of AAA cells have to go to extravagant lengths to run the fuckers, and even a flat Li-Ion is pushing it. Single AAAs even more so. No doubt green will come back into fashion as soon as someone figures how to frequency-double IR up to green for less than a cent.I quite like pure green / emerald green though. Lime green is foul. I probably shouldn't care so much. )
>>25901 Interesting post. Yeah, I'm guessing it was probably just a crap hub that died of its own accord.
>even a flat Li-Ion is pushing it.
Do you mean flat as in complete discharged? I remember reading something about that killing lithium batteries, how do you handle that if they don't have a protective circuit built in?
>>25902 If there's any chance f a customer getting near the battery, then it'll be specified as having protection. It's not completely foolproof, but it's as good as I can get. I don't like locking batteries in if I can possibly avoid it.
The protection gubbins is so cheap (less than $0.10 on a cell price, in volume) that a customer has to really kick against it, in writing, against my explicit, written, unsubtle advice, that it's not happened yet. I really don't want to be caught up in a burning battery shitstorm.
If I can get products to work with supercaps, external power or alkaline batteries, I'll do it. Lithiums are a world of pain - shipping, stocking, manufacturing and recycling all suck.
I kind of assumed most devices would just pack in 18650 or two since they're so cheap due to economies of scale and Tesla and whatnot. Most 18650s I've seen don't have protective circuitry, or at least, not to my knowledge; I'm pretty sure I've seen ones for sale that explicitly state they have a protective circuit in the top.
You're much more likely to see prismatic or pouch cells in consumer electronics. Cylindrical cells just won't fit into most devices. It's usually only big stuff like power tools that use cylindrical cells. Laptops used to use cylindrical cells in a removable pack, but non-removable pouch cells are thinner and lighter. A protection PCB can be soldered or spot welded directly to the cell, as seen in this image.
>>25914 So where do they get used en masse? I know they're in quad copters and that kind of thing, anything else justifies mass production and brings the price down?
Quadcopters and other RC thingumabobs use pouch cells, because you can achieve a higher discharge rate at the same weight. Cylindrical cells are mainly used in bulk applications - electric cars and bikes, power tools, that sort of thing. A cordless drill might use eight 18650s, an electric car might use a couple of thousand. The market for cylindrical cells is gradually moving towards the 21700 size, which is slightly more energy dense.
Pouch cells can be economically produced in fairly small quantities, so you can often design the battery to fit the product rather than vice-versa. This is a big advantage for mobile devices where every millimetre matters.
