Dan's Data letters #100
(page 2)
Publication date: 21 April 2004.Last modified 03-Dec-2011.
Camera choice part 273
If you had to buy a "prosumer" digital camera right now, what model would you choose? And what exactly are "integrated lens" cameras, such as Sony's DSC-F828?
Jordan
Answer:
I might buy a Nikon Coolpix 5700.
Not brand new, but not terribly expensive either, and it's got good macro performance (like most Coolpixes), which is important to me. Most people don't care much about getting super-close to their subjects, though, so there are plenty of options. What you should choose depends on your priorities.
The DPReview camera comparer is an excellent jumping-off point.
An integrated lens camera, also known as a "point and shoot", is a camera where the lens is an integral part of the gadget - you can't remove it. You can often screw on adapters that give you more zoom or a wider view or better macro performance, but you can't change the whole lens as you can with a digital SLR (DSLR).
For most people's purposes, integrated lens cameras are the best choice.
Headphone hiatuses
I have owned two of the little MP3 players you regularly review, and am considering investing in a Little Cute, because I don't lose the ones I have easily enough around the house.
However, one of the players developed a headphone issue that is, to be frank, a little annoying. "Little" is used here as a slight understatement. So is "slight".
I use the MP3 player to run with, and after a few weeks the sound started working intermittently. An emergency fix was to hold the player so that I could apply pressure to one side of the headphone connection, but with little success. I was much attached to my player (it is an original "George", and had been resurrected from a wife-induced-unplug-coma using your instructions) so I blamed my admittedly low quality headphones. I thought perhaps that repeated flexing of the cable during running had fractured the wire, resulting in intermittent contact.
Unfortunately, substituted headphones performed the same. It appears that the 1/8th connection is the problem. Do you have any suggestions for fixing this sort of thing, and assuming that complicated repairs are beyond me, is it at all common? Will the Little Cute player be likely to have similar issues?
Stefan
Answer:
You describe the classic symptoms of a busted solder joint. It
happens to the best of us.
Headphone jacks are usually only held onto a portable player's circuit board by solder. Some solder joints are "dry" naturally, and prone to early failure, but mildly rough treatment of even good joints can, over time, weaken them. Solder's only tin and lead, after all; it ain't a structural material. Result: An annoying intermittent connection.
As you say, you can often make such a connection come good by pushing the headphone plug one way or another, which jams the fractured solder joint back together.
And, again as you say, similar symptoms can be caused by a headphone cable fracture, but you've ruled that out.
If you own a fine-tip soldering iron, you can usually fix this problem by carefully re-soldering the headphone socket contacts on the board. Not all players make this easy (just getting at the board can be a pain with some of them), but many do. Larger devices are still pretty likely to have a good old fashioned pin-through-hole arrangement for their headphone socket; newer and smaller devices are more likely to be surface mount...
...like this. In either case, the solder pads should be big enough to be fixable by anyone with moderate fine motor control.
Just re-melting the existing solder, not adding any more, is often adequate. If you want to get fancy you can solder-suck the existing joints dry and resolder from scratch, which will also allow you to lift off the headphone socket completely, check it for damage and maybe add a blob of glue under it (try not to burn the glue when you resolder the socket...) to make it less prone to the problem in the future.
A professional repairer will probably not do all this; you'll get just a quick resolder job in return for his or her substantial hourly rate (if you had to deal with tiny plastic cases held together by fragile moulded clips all day, you'd adopt the same policy).
If your headphone plug is the usual straight-in type, switching to a right-angle one instead should help to reduce strain on the socket.
Most portable players can come down with this disease. As I said, it's normal for portable player headphone jacks to only be mounted with solder, and it's always possible to fracture solder. It just depends on how you use the player - running with the thing bouncing around in your pocket is likely to be worse than running with it strapped to your arm, for instance.
Bike beam
I've got an electronics question for you. I've got some of those new rechargeable AAs (1.2v) that have 2200mAh capacity I use them with my bike lights in series to produce 12V (10 x 1.2v) and I can run my 10w or 20w (or both) 12 volt lights (similar to MR-11 household halogen bulbs) no problem. With just the 10W I get about 2.5 hours of burn time (10w, 12v bulb draws 0.833 amps, 2.2Ahr/0.833 = 2.64 hours).
If I have a 20 watt 12 volt bulb and I run it at 9.6 volts instead (8 x 1.2v = 9.6volts), how do I figure out how many amps it will draw and how long it should last? Will it still only draw 0.833 amps, or will it draw more to make up for the lower voltage? How do I figure this out?
Shawn
Answer:
This is simple DC electronics, so it's easy to figure out.
Ohm's Law says that voltage (in volts) equals current (in amps) times resistance (in ohms); it's written
V=IR
Now, assuming your "20W" lamp really does draw 20 watts at 12 volts, it'll be drawing 1.67 amps, because watts equals amps times volts (in AC circuits this stuff can get more complex, but it's easy for DC).
Plug these values into the above formula and you get
12=1.67*R
which tells you that the resistance of the lamp is about 7.2 ohms.
Now, incandescent bulbs don't quite work like normal resistors; when they're cold, their resistance is much lower than when the filament's glowing. For relatively small changes in supply voltage, though, their resistance stays pretty constant. It'll drop a bit, but not a lot.
Assuming the resistance stays exactly the same but you drop the supply voltage to 9.6V:
9.6=I*7.2
which gives current of 1.3 amps, and a run time of around 1.7 hours from a full 2.2 amp-hour charge. Your 20 watt rating bulb is now running at 9.6*1.3, about 12.5, watts. Now, its resistance will actually have fallen slightly as the filament cooled, so in the real world you'll get a little more power than that (and a little less run time), but not much.
At this power level, the lamp may seem a bit brighter than a 10 watt globe, but it probably won't, because running it at lower voltage will shift its light output down the spectrum towards red, reducing its visibility. It'll be emitting as much light as you'd expect for the power it's consuming, but a larger portion of that light will be infra-red, which you can't see, and red, which isn't much use. LED lights don't have this problem, by the way.
In other words, you're very probably better off sticking with the 10 watt globe from 12 volts; the 20 watter from 9.6 volts may actually give you a lousier view of the road ahead.
Fiddle-toy search
I saw some magnets referred to as "singing magnets" in Arizona this year and had to leave before I could pick up some. They're football shaped rare earth magnets that when tossed into the air vibrate madly against one another - any help in finding them would be appreciated.
Jerry
Answer:
Were they "magnetoids", by any chance?
Home page here, retailer here.
Battery juggling
I was enticed at Christmas to purchase an Energizer Charger and NiMH Batteries (2100mAh and 30min fast charger). I have been rather pleased with them, if somewhat disturbed by the heat they emit when charging. Since then I have been tempted by sales to buy other non-Energizer NiMH cells. Would these work in the same charger?
I noticed on the package of the new batteries a suggestion about getting their charger. Is this a helpful warning from the engineers, or sales spew from Marketing?
Mark
Answer:
30 minute charging of regular NiMH cells is really hard, especially without fan cooling for the cells; even
a one hour charge will leave the cells too hot to touch. Apparently there's a Duracell-branded 30 minute charger that
has a cooling fan; you picked the Energizer half-hour charger, that doesn't.
If the charger doesn't overcharge, and if the end of the charge is gentler than the start (many ultra-fast chargers don't actually quite finish charging the batteries in the stated time; it's much safer for them to go to 90% charge at warp speed and then ease right off than to charge at full power all the way to the end), you should be able to get away with charging regular NiMH cells this quickly without killing them unduly rapidly. Don't expect them to last for as many charge cycles as you'd get from a decent three-hour charger, though.
It's OK to use other brands of cells with your charger. Cheap cells will probably be beaten to death by the fast charge sooner, but they'll cost less in the first place, so it'll balance out.
Little pins
I would like your help identifying and sourcing a particular computer connector. It's on either end of the cable used to connect an optical drive to a sound card for music input/output. In addition, the same shrouded crimp sockets are on the end of the wires from your case's power/HD LEDs and power/reset switches, which plug into pin headers on the motherboard.
I've done a little searching and I've found a few different references, such as Tyco's MODU connectors and 2.5mm pitch sockets, but I can't nail down what it is. They might be the same thing, or variations on a theme. Also, if you know of anywhere I can purchase these connectors in reasonable quantities I would greatly appreciate it.
Ben
Answer:
The standard four pin audio connector is apparently meant to be a "Molex 70066-G, 70400-G or 70430-G, or equivalent".
You can read more about it here.
This tenth-inch pin spacing is a widely used standard, so it shouldn't be too hard to find plugs - though I confess I don't know where to find them here in Australia.
In a pinch, I think you could cut up 2.54mm connector strips into multiple plugs, but they're not quite the thing you're looking for - for in-line use you'd need to solder and heatshrink the pin connections, not just crimp the pins on and insert them into a housing. That wouldn't take long, though, and you can't beat the price!
Zero miles per gallon
I saw this ad and knew that you are the man to investigate.
Is the "Vaporate System" just pissing in the wind?
Simon
Answer:
I don't know, but you'd think they'd be able to present some actual evidence if the product worked. It's incumbent
upon the claimant, and all that.
Vaporate do actually seem to have an Australian patent (mentioned in this PDF file), but a patent doesn't mean something works. Their site is utterly bereft of independent or even testimonial evidence (testimonials are generally worthless, but I at least expect to see some on a site like this...), and there's no mention of their product anywhere else that I can find.
The only Web sites they seem to have are landrovers.com.au and the identical one you suggested, and the how-it-works description doesn't make a lot of sense; they would appear to be heating the fuel injectors or something, but they don't come right out and say that.
Heck, they don't even say how much more efficient they're claiming they can make an engine. Have they tested their own product? What does it even cost?
Who wants to phone them?
Death by fuzzball
Don't you know that cats carry Toxoplasma Gondii?
I read in a recent article that almost 80% of France has Toxoplasma, with England coming in second with another staggering amount.
When Toxoplasma first invades the body it actually helps the antibodies kill it and force it into a cyst stage. These cysts attach themselves to your brain and according to some studies shown, have been known to affect humans in strange ways.
I went to my doctor and had a blood test. I don't have Toxoplasma, and I for one won't be getting a cat any time soon.
Moishe
Answer:
All cats certainly don't carry the toxoplasmosis parasite; outdoorsy cats often do, but even then it's far
from certain.
The only way to get toxoplasmosis from a cat is by, well, eating its feces - generally because you didn't wash your hands after emptying a litter tray. This, of course, leaves you open to various other diseases not particular to cats.
Most people who get toxoplasmosis (and, as you say, a lot of people do - I don't know about the European numbers, but about a fifth of the US population apparently has the parasite) get it from undercooked meat or dirty drinking water.
Toxoplasmosis is only dangerous (as opposed to possibly quite annoying) to people with weak immune systems - the elderly, AIDS sufferers, unborn babies and so on.
There's no reason for even pregnant women to be worried about it if their only risk factor is living with an indoor cat, though; indoor cats have nowhere to get the parasite from.
There are plenty of real parasites out there that people can get, including a few you can get from your pets, but if you're reasonably hygienic then the risk you run from even a bunch of dogs and cats is small compared with the risk you run by socialising with other humans. There are thousands of dangerous diseases you can get from humans; there are only a few you can get from cats and dogs.
There are a lot of seriously crazy people with firm opinions about human parasites. The truth is that parasites are, for people living in First World nations, not generally something worth worrying about, and toxoplasmosis is one of the less alarming; it seldom does anything noticeable to normal healthy humans.
And, I repeat, indoor cats are typically completely free of all diseases transmissible to humans - and of all diseases transmissible to other cats, for that matter.
