Perhaps, due to microscopic energy flies or evil men with electron-strippers, computers stop working for one reason or another. We combat them with Dan Rutter, who comes equipped with a Logitech MX700 mouse. A mouse you could win, if you get IOOTM.
IOOTM: Ni-Cads Of Doom
I: I've been wondering about the reliability and safety of using rechargeable batteries instead of regular alkaline varieties. Over the years I've come across products that state on the back 'do not use rechargeable batteries'. Some of those happily worked for years using only rechargeables, some would fry the moment you switched them on with rechargeables in them (such as a lot of older pocket TVs). Some products say to use only NiCad and not NiMH, or vice versa.
It certainly seems like a lot of recommendations are made by companies that have their own branded alkaline batteries (Sony, Panasonic etc), so it's very likely they would prefer you to buy regular batteries (their own brand, preferably).
Is there was a way to know for certain that it is safe to use a particular battery type?
Steve Bolton
O: The usual reason for sudden gadget death caused by rechargeables is that the device expects batteries with fairly high internal resistance. It's using that resistance as part of (or all of) its power supply current limiting.
Non-rechargeable batteries (carbon zinc, alkaline, and the not-very-popular rechargeable alkaline) have their own resistance to the flow of current, which is generally a bit less than half an ohm, for an alkaline AA cell ('cell' is the technically correct term for one electrochemical unit; 'batteries' are technically two or more cells put together). This means that even if you short-circuit an alkaline AA, only a few amps of current will flow - and that'll fall rapidly, as the poor cell heats up, its internal resistance rises, and its terminal voltage plummets.
Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH) rechargeable cells have internal resistance too, but it's much lower; well under 0.1 ohms, even for AAs. You wouldn't think this'd be too much of a problem, since the terminal voltage for these chemistries is only 1.2 volts per cell, versus 1.5 volts per cell for non-rechargeables. Less voltage, less current. But problems can still arise with gadgets that draw a lot of current, and with rechargeables that are freshly charged.
Freshly charged cells will have a terminal voltage well above their nominal potential; fast-charged NiMH can easily manage 1.4 volts per cell. If a device expects less than that (because it draws a lot of current and thus causes fresh alkaline cells to sag to, say, 1.3 volts), the combination of high terminal voltage and low internal resistance can allow much more current to flow than is meant to. Result: fried gadget.
The same thing can happen if you use lithium AA cells in some devices. Lithiums have a 1.7 volt per cell nominal potential, and don't sag as much under load as alkalines.You can almost always avoid the death-by-NiMH problem by simply letting your rechargeables stand overnight after charging them, so their terminal voltage settles down. Some devices still need the internal resistance of non-rechargeables though.
NiCd has lower internal resistance than NiMH, but 'peaks' lower after charging as well, all things being equal. So it's possible that some gadgets may actually prefer one technology over the other. This is pretty darn abstruse, though; generally, if it works with one, it'll work with the other.
Wire hunter
I: A few months ago, Atomic ran a series of articles demonstrating a top-to-bottom 'case mod' job, including the installation of a 'wiring pole' to conceal all those messy black, yellow and red wires.
I'm keen to build a similar custom wiring harness for my PC to maximise neatness.Gathering parts for this job has been easy up to a point; Jaycar can supply the needed plugs and sockets as well as the crimping tool and die set. Wire, on the other hand, is being difficult to find! All I'm looking for is a supply of wire to match the colour and characteristics (conductor gauge and insulation thickness) of the wire used to make the leads attached to your average PC power supply. In my search, I've tried electronics stores, hardware stores, electrical wholesalers and car accessory outlets - no luck!Short of ordering from wire manufacturers in the USA, I thought I'd write and ask to see if you knew of any Australian suppliers of the type of wire I'm after.
Rob Amos
O: You won't necessarily be able to match it precisely, but since it's all likely to be cheap 16AWG (American Wire Gauge) and 18AWG PVC-insulated stuff, it's not very hard to duplicate. Medium to heavy duty hook-up wire, with the same cross-sectional area of copper or a bit more, will do the trick. If you want to be able to route the wire around tight corners, look into more expensive silicone-insulated wire, which is commonly available for thrillingly high prices from hobby shops (R/C modellers use it because of its flexibility and heatproof insulation). Most electronics stores don't stock 'silicone wire', but better automotive suppliers might.
The silicone insulated wire will probably have a lot more strands, and they'll be a lot finer; the total amount of copper in there will be the same as you'd get from cheap wire of the same gauge, but the finer strands make the wire more flexible and less likely to fracture.If you don't care about this, though, then just buy cheap PVC insulated hook-up wire a little thicker than what's coming out of the PSU already, and you'll be fine. Hook-up wire comes in plenty of colours, so there's a good chance you'll be able to match the colour of every wire from the PSU.
Surround 'phones?
I: I'm planning to upgrade my PC speakers, and I'm thinking of buying a good set of headphones instead. I've read that headphones are better than speakers for 3D positional sound. Headphones seem to be better in terms of telling whether the sound is from the left or right, but what about telling the front-back location of the sound? Are headphones equal to or better than 4.1 or 5.1 speakers in this regard?My type of games are of the first-person 'sneak-shooter' type like Thief, and positional sound is very important for me. What do you suggest?
Michael Hinojales
O: Headphones are better for all aspects of 3D audio, provided they're being fed by a sufficiently clever positional audio algorithm, and it in turn isn't being fed dumb data by the game you're playing.
On the face of it, this seems silly. Obviously, speakers behind you should be the best at making you think there's a noise behind you, because, you know, there is.
But you only have two ears, on the sides of your head. You don't have any extra fore-and-aft sensors. Your ears figure out where a sound source is by using the oddities of the reflections and occlusions from the pinnae (the external cartilaginous ear parts whose other primary function is to give kidnappers something to cut off and mail to show they're serious), and positional audio systems use Head Related Transfer Functions (HRTFs) to fake the effects that the pinnae have on sounds from different places, so that a transducer firing straight into the ear from the side can make itself sound as if it's somewhere else.
Stereo surround speakers can do the same job with less processing, but they won't necessarily, and they're also likely to have pretty lousy drivers in them (if they're the usual kind of PC satellite speakers). All speaker systems also have channel separation
Issue: 133 | February, 2012