Atomic I/O letters column #162Originally published 2014, in PC & Tech Authority
(in which Atomic magazine is now a section)
Reprinted here March 27, 2015 Last modified 27-Mar-2015.
I've tried little "power bank" chargers from the AA-battery type to the inflated-capacity-number rechargeable lithium type, and been less than thrilled. I've even considered solar panels. But I just noticed that you can get CRANK phone chargers on eBay for, like, two dollars.
It occurs to me that plugging a $US2.11 charger into my much-more-than-$2 phone may be a really dumb idea. On a scale of "fairly" to "disastrously", how dangerous are these things?
I hadn't a clue.
So I bought one of those chargers and plugged into it multimeters, and sundry other testing and torture devices.
There's no guarantee that the many externally-identical crank chargers on eBay are all the same on the inside. The one you buy may be completely different from the one I got. If mine is representative, though, then I would categorise these devices as unlikely to blow up things you try to charge with them, surprisingly entertaining novelties, unexpectedly educational, and even somewhat useful.
But not very.
The normal USB charge rate is the old USB powered-port standard, half an amp at five volts. (The modern USB standard allows for charging at much higher current, though normal USB 3 ports can only deliver 0.9 amps.) Cranking my little charger unrealistically fast can wring more than four-tenths of an amp out of it, but 0.2 to 0.25A is a more realistic figure for sustained cranking of the little handle and teeny geartrain.
So don't expect the crank charger to charge any device more than half as fast as a USB 1 or 2 port. Fully charging a device with a high-capacity battery will take a long time, and probably give you some kind of repetitive-strain injury.
On the plus side, an unremarkable cranking speed will light the red LED on my little dynamo to full brightness, which indicates an output voltage around 4.8 to 5.2 volts, palatable to most USB-charged devices.
The little red light is actually quite a good indicator of output voltage. USB is supposed to be five volts with half an amp of current capacity from an ordinary powered port; USB 3 can deliver a bit more current, and also has special high-current charge-only ports. Many devices with... varying... commitment to the USB specification will draw more than half an amp from any USB port if the port's willing to deliver it; this is important for charging, because the more current you draw, the faster the charge will be.
With no load on it, my little charger dimly lit its LED from a slow crank and delivered two to 2.5 volts. Faster cranking until the light would get no brighter delivered the abovementioned 4.8 to 5.2V. And the output voltage is also, importantly, limited to no more than about 6.1 volts, no matter how fast you crank the handle. This should be safe for almost anything. But the data wires on the crank charger's USB socket are, of course, not connected to anything, so it won't charge devices that demand those wires be connected to a real USB controller.
(Some devices that seem to not be charging from a "dumb" power-only USB charger actually are charging, though; the battery meter creeps up, but the device doesn't otherwise indicate that it's charging. You can get or make USB charge adapters that deliberately connect only the +5V and ground contacts, not the data ones; this lets you charge a device from a computer in the certain knowledge that it has no data connection to the computer, so it will not propagate viruses, or alert network administrators to a prohibited portable device being connected to a top-secret computer, et cetera. The nice steady 5V of a computer's USB port is more likely to persuade a device to accept a charge than the varying voltage of a crank charger, but if a device absolutely refuses to charge without connected data pins, it won't charge with a safe-charge adapter or a crank charger. If you want to get really fancy, check out the configurable USB Wrapper!)
When I plugged in the effective-dead-short of a multimeter in ten-amp current mode and cranked vigorously, the output current peaked at 0.35 amps. So you are never going to get half an amp out of one of these things.
I verified this in a more real-world way by hooking the crank charger up to electric motors, and watching it barely manage to budge the spindle of a motor that'll spin happily from only three volts, as long as the power supply can deliver half an amp and three volts at the same time. For similar reasons, the crank charger could light a standard 5mm 0.1-watt white LED just fine, but couldn't raise so much as a glimmer from a ten-watt LED module with the same nominal voltage requirement, but much higher current demands.
(If you're interested in building your own high-efficiency lamps, by the way, high-power LED modules and drivers for them are now cheap commodity items on eBay. Just don't trust any of them, even if gooped onto a slab of aluminium for heat-sinking, to deliver more than about half of their rated power without overheating. A "50W" module running at half power should last a long time, and deliver as much light as a hundred-watt incandescent bulb. Plug two 50W modules in parallel into a driver meant for one 50W module, and the driver's fixed voltage and current limiting will probably now drive them each at half power. The management makes no guarantees, though.)
When a power supply can't deliver enough current at a given voltage, its output voltage drops to a smaller figure. To use the old water metaphor for electricity, where current is the amount of water that flows per second and voltage is the pressure at which it's flowing, you can think of a power supply as being like a bucket full of water with a tiny hole in the bottom. The pressure of the water coming out of that hole will be high - the misty spray of water may travel quite a distance - but the amount of water per second flowing will be low. Now enlarge the hole to the size of a fist and the flow rate will be far higher, but the pressure per area of hole will be much lower. If the hole were in an industrial hydraulic line with an immensely powerful pump behind it, rather than the output pressure will be about the same no matter how big the hole.
The "educational" part of this thing is that a tiny dynamo charger lets you feel the electrical load. The first couple of turns of the handle are often very easy; then, if you're trying to charge a big-screen phone that turns its screen on when it thinks it's connected via USB, suddenly you're charging and lighting the screen and running the phone's processors, and it's much harder to turn the crank!
So you don't have to keep watching to see if a device is still accepting charge. If it suddenly gets easier to turn the handle, you ain't charging no more. (This probably happened because you slowed down a bit, so your output voltage dropped too low. Lengthy charging of a high-drain device, requires a surprising amount of effort; I suggest clamping the body of the crank charger onto a tabletop or something rather than holding it in your hand, so you don't have to exercise both of your arms at once.)
You can also use the crank charger to power a USB lamp of some kind - one of those tiny third-of-a-stick-of-gun bare-circuit-board lights, which sell for almost nothing, is ideal. Now you've got a perfectly acceptable - I would go so far as to say "surprisingly bright" - broad-beam crank flashlight!
Really, though, this thing is just a toy. A two-dollar voltage-limited geared-up dynamo probably doesn't have much of a lifespan, and its power output is too low for realistic charging of anything but low-capacity devices like "dumb"-phones and e-book readers. (It charges my e-paper Kobo book reader pretty decently!) Oh, and if you're charging something, like a basic phone, via a USB-to-barrel-plug adapter, you don't have to worry about the unconnected-data-pins problem.
The crank charger is lightweight and cheap and a conversation starter, though, and seems safe. And since as I write this they cost about $AU2.50 delivered on eBay, I think you should definitely get one!
(The above information is as always presented with all care but total cheerful irresponsibility, but I wouldn't be worried about trying to charge any USB device with one of these things. It might not work, but it doesn't look able to kill a phone. I've bought a couple more of these things since I first wrote the above, and they all seem the same, except one is noticeably noisier than the others. The geartrain inside it looks exactly the same as the gears in the others, so perhaps the bearings in its little generator-motor are dodgy, or something.)
Carburettors are like this, too
More than once I have done this, and it mystifies me. A PC is unstable, crashing with errors indicating memory or video problems or just freezing randomly for no reason. And you open up the case and swap out the RAM or video card or whatever for another one. And now it works. To make sure, you swap the old hardware back in again. And it STILL works. Problem gone.
Why the hell should this be the case? It's like the universe is playing a "have you tried turning it off and on again?" game with me. If anything, handling the hardware should make it LESS reliable from static damage, right?
Yes, handling the major components of PCs without taking electrostatic precautions is likely to slowly degrade their reliability. Tiny electrostatic discharges you can neither see, hear nor feel can damage the minuscule transistors, rounding off the nice sharp corners that all of the vital high-speed digital signal waveforms should have.
The peculiar take-it-out-and-put-it-back-in-again fixing technique you describe, though, is a much simpler electromechanical process, called "reseating". Basically, there's gunk on the connecting terminals - or something's become partially unplugged - and removing and replacing the component wipes the gunk off and/or gets the component solidly back into its socket. This can work for all kinds of dirty terminals - mains power plugs, audio leads, you name it - but computers are a particularly extreme case.
A modern PCIe x16 slot, for instance, has 164 contacts in it. Many of those are pretty-low-current power-supply contacts or interleaved shielding grounds, for which a bit of contact dirt doesn't make much difference. But there are also getting on for seventy high-clock-speed digital data contacts, all of which are essential for a video card that uses all 16 PCIe lanes. If a few of them are dirty, every now and then some bits will be dropped on the floor, quite possibly resulting in a hung computer.
If you remove and replace the card, or even if all you do is unscrew it, unclip any mechanical slot-locks, and squish the card up and down in the connector a bit, then you wipe the dirt away.
Reseating can make things less reliable as well, mind you. If you remove a slotted component from a dusty PC then plug it straight back in again, you're likely to squish some dust into the contacts, which is bad news. Cack-handed attempts to remove dust can also just move it around and contaminate empty slots. So if your computer only crashes very, very seldom, fiddling with its hardware is unlikely to make things any better.
If the darn thing's hanging all the time, though, especially if you recently installed some new hardware, unplugging that hardware and plugging it back in again - or unplugging it, blowing clean the slot and card contacts, and then plugging it back in - can indeed cure the problem.
I know how to block popup ads. How do you block "slide in" ads? You know, those things that slide in when you scroll to the bottom of an article, or long before, to offer you priceless opportunities to buy products or subscribe to newsletters and annoy you even more?
Any modern ad blocker should be able to do this - the popular Adblock Plus definitely can, for instance - but it probably won't do it unless you tell it the element you want blocked. Ad-blockers don't default to blocking slide-in stuff, because it's more likely to actually be something the reader wants to see than the classic slab of Flash coming from crapserver8.annoyingads247.com.
Add-ons like Adblock Plus let you just click on any "element" of a page to block it, and refine the resulting block rule into a filter that will catch, say, everything from whatever server burped up the thing you just clicked. Adblock Plus also has an optional "Element Hiding Helper" that makes it easier to target squirrely envelope-pushing things, like those evasive slidey ads.
Sniping ads individually can be tiresome even with helpers like this. One old-school but still effective way of blocking whole ad-serving companies is to edit your hosts file. The hosts file, a simple text file anybody can edit in Notepad with no danger of irreversibly damaging anything, can be used to point the domains used by whoever you don't want to hear from to an IP address where no such nuisance can be found. I've written about this before, for instance here and here.
Chrome is pink. I have no damn idea why. It is driving me crazy.
There is nothing wrong with my monitor. Photoshop works fine, including all the colour-management stuff. Likewise MS Office and all the other productivity software I use. But when I open Chrome, all of the colours are overlaid with salmon pink, as per the attached screengrab.
I have verified that this screengrab looks just as pink on other computers, though none of their programs are pink.
I've seen colour-management mistakes that totally foul up the palette so everything's shades of one colour [here's an example of that - Dan], but why would it affect nothing but Chrome? I'm at my wits' end.
A little further research, involving installing some 3D software (Bill doesn't play 3D games, but Google Earth worked), verified that Bill's problem was that anaglyph 3D had been turned on. For some reason, if Chrome has Settings -> Advanced -> System -> "Use hardware acceleration..." enabled, it pays attention to that setting and colour-overlays itself, though few to no other 2D programs do.
Anaglyph 3D is the kind that works with glasses with two different colour-filter lenses, usually red and cyan-blue. Anaglyph doesn't work terribly well, but you can use it with anything that can display or print a colour image, and very cheap cardboard glasses let you view it, so it's been popular for well over a century.
Modern 3D-vision graphics-drivers often support anaglyph along with the better kinds of 3D, like LCD shutter-glasses or polarised displays. (Polarised displays are the system used in normal 3D cinemas; the glasses are still cheap, but the display is not).
In the current Nvidia drivers, for instance, you turn 3D-mode on with Nvidia Control Panel -> Set up stereoscopic 3D -> Enable stereoscopic 3D -> Discover glasses. Untick "Enable stereoscopic 3D", and the problem is solved.