Made By Monkeys

"FORCE's EMF-7 compound provides mains with a stable molecular structure. Each threephase system is divided into four modules R,S,T,N. The weak electric current generated by EMF-7 (0,06-0,09 mA) extends the FORCE system lifespan by 30-100 years." [The Force Efficiency System]

"Found this box lying around work. It's quite a powerful charger at 16,000 mA but I really don't think it will be any match for my 16,000,000 μA charger I have at home."

"I had previously noticed that the radio's mains adaptor got a little warm when it was plugged in," writes Mike. "But a quick check on the manufacturer's website confirmed that this was 'normal'. In my mind anything that gets warm must be consuming energy,  so I thought to myself "time for some more detailed investigation."

My bench power supply (carefully set to 9V output) and connected directly to the radio reported a current consumption of about 200mA during normal reception at low volume (1.8W), which only reduced to 140mA when it was 'sleeping' (1.3W).

 

Given my run-ins with mechanical locks, I am especially leery of electronic locking systems.

You might be too, after reading:

Jon Titus points us to a function on the Das computer keyboard: that might leave us ten-fingered folks scratching our heads:

Here's a typical plug strip with six receptacles.  But try using three-way adapter to add two extra outlets for a total of eight and what do you get? Only one extra outlet.  Definitely designed by monkeys!

DEV-Monkey Editor Jon Titus posts a great rant on his blog about the lousy state of schematics that come with electronics development kits and boards, particularly when trying to print them out.

Having started a dev kit project earlier this year, I absolutely agree!

Writes Jon: "Most of the schematics I see fall into the "awful" category. Lines appear tiny, legends seem unreadable, and part numbers and pin designations look like smudges.  I use an HP LaserJet 1100 printer and it produces clear, clean diagrams from schematic-capture software.  But the schematic diagrams that accompany development kits or evaluation boards look more like bits of gray connected by what might be lines.  To me, these schematics are unreadable and thus, useless."  Read more....

So can someone tell us-- just why are they so bad?? And what could be done to make them better?

                                                                                                                           

So it was pretty impressive to come across some pix and description of a swollen iPod Nano battery posted by David Kerry in his blog post iPod Cause of Death: Dangerous Battery. He figures it swelled to 3X its original size. (Check out the other great photos here too!)

After removing the iPod's cover (which didn't take long for obvious reasons), Kerry writes:

"What I was greeted with inside was rather shocking. It would appear as though my battery has swollen to around three times it's original size and I've narrowly escaped a melting or exploding iPod. The swelling had not only wedged the select button permanently out rendering it, and the iPod useless, but also the front of the casing is actually cracked, a fact I had not initially noticed as it's not easily visible on the white backing.

"I was working as a Staff Consultant for a small microwave company.  One of my contributions to the company was a design for a line of very low noise phase locked oscillators featuring the company's signature air strip resonators.  The line was going well under the leadership of a super tech who knew it well and could fix any problem they encountered.  I was therefore surprised one day when the Director of Engineering came to me in a panic: "The phase locked oscillators are all very noisy at cold operating temperatures."

I walked slowly over to the lab.  As I approached the set up, I could see the noisy spectrum analyzer display from across the room.  I could see some other things about the set up as well.  The set up included a refrigeration-driven temperature chamber and was set up with a stack of power supplies so that multiple units could be run over temperature at the same time.  I approached the set up, carefully adjusted the stack of power supplies so that they rested squarely on top of each other and walked away.  Problem solved.

Besides loads of useful stuff over at www.microwaves101.com, the authors have posted what they call a "politically incorrect"  microwave slang glossary.  While it predictably features some of the usual crude and sophmoric lab humor, there's a lot of amusing terms that will ring familiar to most engineers -- myself included.

A Simpsons fan, I'm particularly fond of Bart's Head: 

"'Bart's Head' is the colloquial term for the waveform in the frequency domain of a CDMA signal as viewed on a spectrum analyzer. When operating correctly, it looks a lot like Bart Simpson's head. Square sides, kind of choppy on the top. You might hear something like; " I looked at the Bart's head at the antenna port, and it rolls pretty sharply, I think the duplexer is tweaked" "

No wonder banks are having such a tough time of it these days! Mike Meakin sent in this head-scratching HSBC advert from the Sunday Times:

"I'm fascinated by the 3 pin in-line plug - never seen one of these in my travels! What do you suppose the graphic designer thought this adaptor was supposed to do? Or am I missing something?"

EDN Editor Margery Conner juxtaposes two recent quotes relating to the amount of energy stored in a laptop battery pack that couldn't be more diametrically opposed in her PowerSource Blog post Hand grenade or coffee thermos: Two very different models of a laptop battery.

First from a NY Times article about solar thermal energy generation:

"A coffee thermos and a laptop computer's battery store about the same amount of energy"

Second from an IEEE Spectrum article

"...the energy density of lithium-ion batteries used for laptop computers, at 40 watt-hours per kilogram, was already getting uncomfortably close to that of your basic hand grenade."

Both analogies have their flaws, of course, as EDN readers gleefully pointed out in their response to Conner's provocative post.

   Products designed with a dual purpose usually don't do any one thing particularly well -- think sporks. Though that wasn't exactly the case with this solar dual-purpose flashlight/bicycle light that a blogger who goes by the moniker le magicien purchased, he discovered it worked a whole lot better once he redesigned it:

"I bought a nice solar powered waterproof flashlight with an incandescent bulb on one side and 3 bright red blinking leds on the other. It uses 2 AA size rechargeable NiMH batteries (1.2V 600mAH) being recharged by the solar panel and also has a conventional battery holder for 2 more AA size cells in parallel with the rechargeable ones. Thus, if the conventional cells are low you may always recharge the other battery holder. Suggested uses for this torch are: bike, car and at home.

I like this torch a lot but... the incandescent bulb eats the NiMH cells pretty fast and the blinking leds... who needs them? So the idea was.. why do not replace the rear red leds with white ones? There's only one problem - white leds do not work with less than 3.2 volts - therefore some kind of voltage booster was needed."

Here are links to the circuit schematics used in the redesign, plus some great photos of the modification work! 

Rather than braking, some vehicles rely on plugging, which involves reversing the motor voltage to power to a stop. In the Design New Calamities column, The Case of the Culpable Contactor, Forensic Engineer Myron Boyajian recounts his investigations into a fork lift that was plugging rather too quickly -- almost dumping unsuspecting drivers to the floor. 

"Because two drive motors were used, our designers used a dual-drive contactor system with separate contactors for each motor. In sharp turns, power to the inside motor would be cut to prevent wheel spin...During my tests, the motors correctly stopped and started as the wheels were moved through their steering arc and I saw the plugging contactor pick up and drop out during plugging. Motor control should have been normal. With a bright light and close examination, I found a heavy deposit of corrosion on the plugging contactor tips, possibly due to salt-air contamination, that prevented an electrical tie between the armature circuits during plugging."

Boyajian cleaned the contactor tips and, not surprisingly, plugging returned to normal. But it raised some interesting questions about the choice of dual motor control in the first place.

As he describes in his EDN Tales From the Cube installment "Silence in the Sanctuary," Neubert describes his successfull efforts to locate (and mitigate) the offending party

The solution? A custom Faraday Cage, of course. Problem resolved.

View large image Richard Langner figured out how to cleverly convert his PS2 keyboard into a  true "cereal keyboard." To achieve this conversion, he rearranged the key tops and then re-mapped them in software.

Suprisingly, he says, not many people notice the difference!

  EETimes reports the real reason behind the disastrous, $1B-dollar Xbox 360 recall last year. Unfortunately, it's all an all too familiar tune these days with unrelenting pressure on design engineers to cut costs and speed design cycle.

Writes editor Junko Yoshido in "The Truth About Last Year's Xbox 360 Recall": cut costs and speed design cycles:

"The Xbox 360 recall a year ago happened because "Microsoft wanted to avoid an ASIC vendor," said Lewis [research vice president and chief analyst at Gartner]. "Microsoft designed the graphic chip on its own, cut a traditional ASIC vendor out of the process and went straight to Taiwan Semiconductor Manufacturing Co. Ltd., he explained. "

A candidate for the fake shake-to-light flashlight hall-of fame. Note that the circuit board has no actual traces! See more examples at Instructables.

David Mery works in an office where the light is controlled by a single motion sensor that is relatively far from most of the desk-bound employees. When he wrote to the people managing his office to complain that one had to stand and flail about or lob a basketball at the sensor else work in the dark, particularly in the short days of winter (and sent this photo in to prove it), he received this illuminating explanation:

"The sensitivity of the sensors is set centrally for the whole building and is fine for most.

Oh well, David, there's always night vision goggles!

Here's a look at David's office with the lights on and the mal-positioned sensor:

Warning: EMI, that silent and pernicious killer, may be stalking your chihuahua.

Thank goodness the people over at the Bargains Xtreme website are now offering a pet-specific device designed to keep Fido fit and free from dangerous electromagnetic waves. It's especially recommended if your dog has daily cell phone usage!:

"That’s right the company that brings you the Q-Link for humans has just introduced the Q-Link for animals. A Q-Link pet trial was conducted with the idea that new Pet specific Sympathetic Resonance Technology can help protect animals from harmful Electro Magnetic Frequencies, hip aliments, along with many other beneficial effects. The results were overwhelming. Did You Know? Q-Link technology has been used on racing horses for years to reduce stress and increase performance? The all new Pet-Link is compact and light enough for every size pet (22mm x 22mm, 8mm thick - 6.4 Grams) and features a durable waterproof rubber casing with fitted clip ready for your pet's collar."

Of course you could save yourself the $59.95 and wrap your dog in aluminum foil.

Sister publication Design News reports in its Lead Free Zone Blog that The Irish retailer, Boots, has the dubious honor of becoming the first company in the EU to prosecuted for violating the Waste Electrical and Electronic Equipment (WEEE) Directive, which aims to divert electronic devices away from landfills:

"The retailer pleaded guilty to charges brought against the company by the UK Environmental Protection Agency (EPA). Boots officials admitted the company failed to post a notice in their shops alerting customers that the prices of electronic products include a contribution to a producer recycling fund that ensures old electrical and electronic products are collected and recycled appropriately. Boots also failed to include a notice in a newspaper ad that a contribution is made to the fund from add-on’s to the retail price. Notices in shops and in advertising is required by WEEE."

While there's evidence that some low-cost lighting products made in China are of dubious quality, I have no data, anecdotal or otherwise, on quartz clocks manufactured there.

Though if a clock costs you only $1, I suppose you can expect to get what you pay for.

José Pino has apparently run into more than a few cheesily-made quartz clocks, or just has had extremely bad luck, as he's come up with a nifty circuit to get one-second (1hz) pulses from a broken quartz clock. He writes:

"Quartz clocks break easily (especially if made in China) after a while. The gears lose lubrication and the dust gets the job done. Fortunately, the electronics of the clock work for many years without problem, so you can "hack" a quartz clock to get a timebase generator, which can be used in any project that needs exactly one-second pulses."

Check out the full instructions (including step-by-step photos and circuit diagrams) and other gadgets on his website.

Sister publication EDN presents an engineering who-dunnit in its latest Tales from the Cube, involving two engineers who were asked to investigate why the company's telephone switches were failing to switch activity from one machine to another.

Read about their full investigation here.

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Are there any real magnetic induction shake-to-charge flashlights out there? Phil Karras relates his run-in with some more flagrant fakes on his website:

"I'm not saying that the flashlights were not worth the $2.50 I paid, but they were not as advertised. The flashlight box clearly stated in poor, but understandable English, that the flashlight did NOT use batteries, all you had to do to make it light was to shake it back and forth.

On my way out I heard someone say that there was no magnet inside the flashlight. Instead of going right back to the vendor, though, I went home and ran an experiment. I left one of the flashlights on while I went out for a couple hours. When I returned, the flashlight was dark. I picked it up and shook it, but no amount of shaking would make it shine again."

Warning: Toaster covers may be dangerous to your health. That is, if you own a Salton Cook's Essential 4-slide-wide electric toaster, which was voluntary recalled because of a tendency to turn on automatically and ignite items placed on top of it. The toaster was made in China.

According to a release by the U.S. Consumer Product Safety Commission, in cooperation with
the online retailer QVC:

QVC has received information that ten toasters reportedly turned on spontaneously, including one incident of fire damage to kitchen cabinets and two incidents of toaster covers burned. No injuries have been reported.

Maybe a toaster cover just isn't a good idea after all, given this online review
at eopinions:

John Goldsmith sends in this example of a shake-to-light torch he purchased at a filling Station - it was a cheap offer if you bought enough petrol. Well, he got what he paid for.

"As the closeup photo shows, the power comes from a magnet and coil, being stored in a 0.22 Farad (not microfarad!) capacitor on the PCB. The on/off switch has a little magnet on the slider and a reed switch on the PCB. This maintains the integrity of the watertight housing. The operating magnet is actually some small powerful magnets embedded in a larger lump, presumably steel. A nuisance as it drags all the recent UK coinage out of your pocket. I'm sure the unit would be more efficient with metal springs as end stops - the rubber used seems to absorb all the energy. I recently bought a wind-up 3 LED unit which is much brighter and much longer running (and less embarassing to operate).

Having looked closely, John also discovered a problem with the magnet.

David Merrill discovers unintended sound effects from an LED display:

"I didn't realize that an LED could make *audible* sound until my friend/colleague Sajid called me over to have a look. What can I say - it's true.. This is a circuit with NO SPEAKERS, making audible sound.

Watch (er, listen) to the video.

England's commissioner for children and a civil liberties group are taking their jobs way too seriously:

According to the AP, they're mounting a campaign to ban the Mosquito -- a device intended to repel packs of yobs by emitting an intensely annoying high-frequency (17.4 kHz) tone.

Old people are immune to it, because the ability to hear high frequencies drops off as the birthdays mount.

"This device is a quick fix that does not tackle the root cause of the problem and it is indiscriminate," English Children's Commissioner Al Aynsley-Green said."I'm very concerned about what I see to be an emerging gap between the young and the old, the fears, the intolerance, even the hatred, of the older generation toward the young."

The British government subsequently told the BBC that it has no plans to ban the technology, though it stressed it should be used as a "last resort."

But in a delicious twist of irony, young people have found a way to leverage the technology to thwart oldsters.

When poorly aimed, a flashlight's multiple light sources can create a serious Van Gogh effect!

Doug Ritter writes about the clone flashlight that produced this hallucinogenic effect on his equipped to survive website, where he reviews outdoor gear and survival equipment. He writes:

"The "Pilot" lights by Holly Solar Products are a virtual clone of the original triple AA-cell Trek light, though of lower quality fit and finish, with a twist. Besides the Pilot 2 ($30) two-LED model, they also offer both a one- and a three-LED version. The single LED model, Pilot 1 ($20), didn't seem to offer much except extra long life and it was quite bulky for the light provided. The Pilot-3 ($35) served as an excellent example of the difficulty that having multiple light sources that are not well aimed can cause, as it provided three distinct lit areas. Not too bad for finding your way, but seriously annoying when trying to use the light for close-up work."

Having been born and raised in Minnesota -- Land of 10,000 Lakes, as modestly claimed -- I've always had a fondness for fishing. We mostly caught sunfish and walleye.

Though I had a strong aversion to baiting the hook, when I saw this circuit designed by engineer Dave Johnson, who runs the website Discover Circuits, for harvesting your own bait, I just had to pass it along! Explains Dave:

"When I was a kid my engineer uncle built a circuit similar to the one below. My cousin and I used it to force earth worms out of the ground to be used for fishing. It worked like a champ. Please be careful since there is high voltage at the probe tips."

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If an incredibly low price isn't an obvious enough tip-off, here's a surefire way to tell a cloned product from the real thing: In a lame effort to "prove" that the fake has been through some sort of rigorous quality-control process, it usually carries at least one official-looking label to that effect.

Take this $20 clone of the $270 U2 SureFire Ultra LED flashlight, which is one of the toughest and brightest flashlights out there. The clone is the one in front with the gold "Q.C. Passed" label on its bezel.

Of course, there's other telltale signs that this Chinese-made light doesn't come close to the real thing, as Craig Johnson, operator of the website www.ledmuseum.org, a site devoted to all things LED (including some highly entertaining reviews of LED-based products), discovered on closer inspection:

From the department of "If you've ever wondered why China makes things so much cheaper than we do."

A frustrated design engineer whose company uses a proprietary lithium-ion battery made in China complained recently here in the Made by Monkeys blog about significant problems with those batteries swelling up.

Bloated batteries sound like fodder for yet another “Made in China” recall story – and it’s not inconceivable that some manufacturing defect could turn out to be the culprit in this case.

But when it comes to lithium ion batteries, it turns out that how you charge one can mean the difference between a well-functioning device and one that bears a resemblance to a certain top criminal underlord in the galaxy.

Design engineers often complain that development kits that rely on a host PC provide no isolation. The resulting ground connection between the dev kit and PC can wreak havoc on the dev kit and, worse yet, fry your PC.

Jon Titus, who blogs over at EDN's new DEVmonkey site and has used and reviewed plenty of dev kits in his day, describes the problem and suggests two solutions for frazzled engineers trying to track down elusive grounding problems.

Rule No 2: If you have ignored Rule No. 1, expect your device to be defective in the exact same way as the display model was, and to exhibit that particular defect very quickly

I bought this Orvis LED timepiece from a Levenger store, with the optimistic idea that I could use the carabineer spring clip to hook it onto my bag and put something prettier than my old plastic-banded digital watch on my wrist. The LED light was just one of those nice, but not must-have features.

Guess I wasn't as good of a girl last year as I thought I was -- Santa skunked me with a broken toy in my stocking.

This little $7.95 gizmo called a Battery Eater made by Kikkerland is just the thing for the environmentally concerned -- you stick an old battery in and his ferocious red LED eyes blink.

Yeah, right! Note how the eyes above are dull and not the least bit ferocious-looking! Though this thing is described as a device for "sucking the last bit of juice out of your old batteries," the only thing mine did is suck money out of my husband's pocket!

Last night the new Times Square New Year's Eve Ball, commemorating the 100th dropping of the Ball, successfully helped ring in 2008. The new Ball is brilliant, literally: It sports 9,576 LEDs in place of the 600 incandescent and halogen bulbs of the previous Ball.

But the marketing claims about its "greenness" are nothing short of ridiculous.

Craig Johnson, who runs the website www.ledmuseum.org, where he posts some highly entertaining product reviews, had a few choice words to say about this Chinese-made flashlight advertised as "no battery needed."

Discover Circuits founder Dave Johnson found this broken solar powered path light near a railroad track. Like many engineers who find things and think the parts might one day come in handy, he stuffed it in his pocket. (Why does broken stuff seem to have a natural affinity for railroad tracks??)

Upon closer inspection, he realized that instead of filling the 3-square-inches of available space with solar cells, the unit skimped out, using four skinny cells that yielded an active area of only .83 square inches (28%).

Engineer Scott Wayne, bought this inexpensive (<$200), FineDrive 400 aftermarket GPS system for his car last year -- only to find out quickly what sorts of unhappy performance trade-offs the manufacturer had made to get to a lower price point:

The holidays are just around the corner, which means it"s time to find out how many light strings survived 11 months in the attic. When we find a clunker, the quest for the bad bulbs usually leads to some really creative expletives at my house.

Bad. Bad. Bad.

That's how Dave Goldstein describes recent problems with a coolant leak in his Apple Power Mac G5 -- the first popular computer to incorporate water cooling as a standard thermal management strategy.

He writes:

"The late G5's are very messed up. Oh man. I don't what the liquid is that sometimes leaks from the cooling system, but it's corrosive. Don't know whether it's a poor engineering design or a manufacturing defect. I have an earlier G5 with no problems."

Over two million pets in the UK have an idENTICHIP RF tag in the scruff of their neck that works as a kind of electronic ID tag. So what are the chances that two new devices based on the same technology -- which has had a good track record up until now -- would fail in three different dogs (including Barney, shown here with his pal Georgia, who coincidentally lives next door to one of the other dogs). And then to have those same devices weirdly and spontaneously rectify themselves after "xray"' investigations?

The odds must be, well, big enough to be almost impossible.

In honor of Halloween and a step-function-up from those truly dreadful store-bought special effects, here's a great little project from the ghoul's workshop of Clive Mitchell. This USB powered, fiber-optic slug is guaranteed to inspire envy, awe, possibly even fear amongst your co-workers.

View lit necklace

You know what's scariest about Halloween? The avalanche of cheap seasonal merchandise (like the LED necklace shown here) that descends upon the stores around this time. This ever-increasing parade of gawdy, noisy schlock underscores just how low some companies have stooped by trading off any semblance of quality or actual fright-inducing gore in favor of tawdry, unrealistic special effects, To wit, just this weekend I saw on display an offensive rubbery-lipped, talking slug. A nasty piece of elastomer, IMHO.

It's a terrible twist of irony. The Chinese can't seem to keep the lead out, while everyone else may be doing too good of a job keeping it out. So reports the LA Times, in the article Lead phase-out may destroy electronics. The problem? Tin whiskers, like the ones on terminations, shown here..

Click to view parts

Not dazzled by the special effects of a cheap fibre optic light, Clive Mitchell decided to hack his own:

"Fibre optic lights like this one have been about for a long time. They were originally made using glass fibres illuminated by a candle shaped light bulb, but these days the fibres tend to be plastic with a focused low voltage lamp as the light source.

These cheap gimmick fibre sprays are available in the UK from "one pound stores" which would probably equate to "dollar stores" (make that 'two dollar stores' with the current exchange rate!) in the USA. They tend to be battery powered and have a few flashing coloured lamps inside.Inside are three self flashing lamps with small bi-metallic contacts inside. They pulse and flash irregularly, making the fibre optic spray pulse in a rather vulgar manner. It's a complete waste of a good bunch of fibres, so I developed a project to convert one to LEDs and make it run directly from the mains.

The whacked-out temperature controls on EE Mike Kotecki's Viking fridge were keeping things just a little too cool:

"We moved into a new, used home two years ago that had a built-in bar in the living room. (Talk about closing tactics!) Anywho, it had a very nice 15-year-old built-in “under-cabinet” Sub Zero beverage refrigerator, that, as far as I could tell from the constant hum, cost about $400/month to keep my beer and tonic cold. So, I went out shopping and soul searching for an energy-efficient replacement.

Andrew Morris cautions readers to beware when you see one of these made-in-China (shocking, isn't it?) mini-drills as engineers made some bad trade-offs in the design.

"I see many of these things at flea markets and garage sales. Highly useful for PC work, but I think people buy them and then are disappointed with their performance. The motor screams at high RPM unloaded and the small 9 or 12 volt AC adapter is almost useless. It is so underpowered that the drill motor slows to a crawl, not to mention that it has no speed regulation.

The recent brouhaha in this blog over the underwhelming performance of lithium ion batteries and the care that must be taking when charging them reminded me of a case in Design News that involved an explosion of near-Hindenburg-like proportions

Oh I know what you're thinking -- it's those incredibly thermodynamically unstable lithium ion batteries up to their old tricks again. Wrong!! This culprint in this case was a lead acid battery for a lift truck.

Let's just say the sucker really got shredded, as noted by Myron Boyajian, the forensic engineer who was called in to investigate the case on behalf of the singed plaintiff:

"If a lead-acid battery could discharge and charge with perfect electrochemical efficiency, there would be no emission of hydrogen or oxygen gas, just the quiet conversion of the plate material, one of lead and the other of lead oxide, both to lead sulfate while the sulfuric acid electrolyte changed to water while discharging; and the reversal of this process during charging.
One hundred percent efficiency, like perfection, is only to be hoped for. Excess or rapid charging/discharging, plate age and condition, excessive temperature, and other reasons may cause hydrogen and oxygen gas to be emitted from a lead-acid battery."

And kapow!

Roger Platt gleefully spotted this heavily shaded, solar-powered parking meter in Bargates Car park, High Street, Burton upon Trent. He wonders if the fact that the area is famous for beer and brewing had something to do with the decision to locate it under a leafy canopy and notes the irony in chopping branches or cutting down trees to accommodate these environmentally-friendly devices.

The website Ecofriend also notes that the UK's notoriously gloomy weather has plagued the performance of these meters. Adding further to the woes -- Platt says he's noticed a number of these panels installed facing North, something he says "your average Boy Scout can figure out is not the best direction to point a solar panel."

The announcement last month that 46 million Nokia-branded lithium-ion (Li-ion) batteries made by Matsushita Battery Industrial could potentially short circuit and overheat was just the latest in a spate of product advisories and recalls of the technology over the past two years.

But it’s not as if Li-ion batteries are at the early point in their life cycle when you would expect these sorts of problems to crop up. Sony invented the technology back in 1990. So why is it failing now?

The theories behind the technology’s recent spotty performance are complex and varied, which makes fixing the problem a perplexing engineering challenge.

Engineers buy and use development kits and evaluation boards to minimise their risk and speed the design cycle -- many say they expect to get something working on a new board in a mere 30 minutes or less. So when the documentation sucks, often contradicting itself or leaving out critical details, it can be insanely frustrating. And it's especially wrenching when the hardware is interesting and useful, as engineer/writer Jon Titus recently discovered trying out a new microcontroller dev kit from Freescale.

"I have a Freescale kit here that could let engineers compare performance of
8- and 32-bit MCUs in the company's new Flexis family. The same code should
run in either processor type, which sounds like an interesting capability
for engineers. But the written instructions are so awful many engineers
will give up. And, nowhere in the instructions does the kit explain its
purpose or provide examples readers can use to compare performance, code
size, and other characteristics for each of the two processor types.

Engineer Andy Morris recently discovered an unwelcome feature among several Chinese-made stereo sets he owns: Shoddy design work.

Andy bought this Emerson model ES50 stereo new and to his dismay after 9 months of fairly light CD use (no teenagers in the house, presumably), the CD player literally melted.

Where to begin, really, in our recitation of the design flaws? Starting with the miserable execution of a compact footprint [...the designer just squashed the transformer down and spread it out sideways to fit the envelope and get the desired wattage] to what can only be described as thermal mismanagement, to the inexplicable use of certain components, the list of egregious design errors goes on and on. My these monkeys were busy.

Andy describes the key design flaw that resulted in the player's quick demise and some scorched pinkies (his): "The voltage regulator output transistor was mounted on the copper side of the PC board with a small amount of copper (almost none) used as the heat sink. It was required to drop 10 volts at 500mA, dissipating 5 watts of power. It failed and shorted out, applying 18 volts instead of 8 volts to the CD circuit, essentially frying the CD player. The voltage regulator circuit is similar to the one shown here except for no Q1, D1, D2 and a different zener diode. View circuit

Click on the link below to see Andy's redesign of the circuit and transformer, though his warning to the wise: Stick with quality brands like Sony and Panasonic.

EDN Editor and Blogger Paul Rako seems to have the same sort of luck that I do -- we both are constantly under seige by an army of appliances from Hell. In his latest battlefield skirmish chronicled in his Anablog blog, he describes how a failed override switch in his Maytag refrigerator brought a whole new meaning to the term "automatic ice dispenser."

Those portable shake-to-charge devices seem like a good idea, especially for the battery challenged, but how well does this sort of thing really work? Engineer Dave Johnson took this flashlight to the test and found the performance decidedly lacking:

"The maker used some very cheap 1N4001 diodes in the bridge rectifier circuit instead of more efficient Schottky diodes. They also used a small 0.5 Farad cap with a 5.5V rating. I noticed that that this kind of super capacitor was originally designed for maintaining data in memory chips and has a rather high internal equivalent series resistance. This reduces the overall efficiency, since the device can't be charged or discharge very quickly. Some of the power that should go to the LED will end up being dissipated inside the capacitor. Better super capacitors do exist.Most white LEDs draw about 20ma of current with a voltage of about 3.6 volts. As the voltage drops from 3.6v, the current will also be lower. Without any regulation, the circuit will not have a consistent light output. I measured the LED current in this circuit at only a few milliamps, even after many minutes of vigorous shaking. This suggests that they decided to sacrifice light intensity for light duration.
View circuit

The human mechanical power to electrical power conversion efficiency for a shaking device, such as this flashlight, is poor. To measure how much power I could get from the shaking magnet generator, I first completed the flashlight dissection process by disconnecting the coil from the flashlight circuit. I then connected the coil to a Schottky diode bridge, made from four 1N5817 diodes. These diodes have a much lower 0.35V drop instead of the 1.0V for the 1N4001 diode. I then placed a high quality 10 Farad super capacitor from Maxwell (www.maxwell.com) across the output of the bridge.

To measure the capacitor voltage, I connected a digital voltmeter across the cap. Before the test, I made sure the capacitor was completely discharged. I started a stopwatch, and then started shaking the flashlight's magnet. After 120 seconds, the capacitor was charged up to 1.0 volts. This corresponds to an energy increase of 5 joules using the equation 0.5CVV, where C is 10 Farads and V is the 1.0 volts across the capacitor. So, I got 5 joules (watt-seconds) of energy in 120 seconds. That means that the magnet shaking was only able to produce about 0.042 watts of power. This is a dismal amount -- and I am no weakling! To put this into perspective, a single 1.5" x 1.5 " solar cell, placed in bright sunlight, would generate more power than the shaking magnet generator. I bet many of the hand crank generator flashlights I have seen for sale would do much better. A pull string type generator would work even better.

But let's imagine a different kind of flashlight altogether.

Bad LEDs don't die. They just fade away and sometimes exceedingly quickly, like this LED nightlight example. Observant reader Clive Mitchell sent in this rather amusing example of a large display LED clock gone all wrong:

"This white LED digital clock displaying departure times at the Glasgow Central Station is clearly suffering from LED fade in a large scale manner. The clock, installed in 2005 and subsequently junked, was one of the first uses of low-quality, Chinese white LEDs. Up to this point, the traditional Gallium Arsenide LED had been considered almost indestructible. So it was a real kick in the teeth to a lot of companies when unreliable LEDs hit the market. I, too, got my fingers burned when I used a load for a TV production. Fortunately there were enough in the application to compensate for the ones that failed."

Low-quality LEDs are something that some manufacturers today admit is problematic, in large part because the design flaws are not evident until after thousands of hours of testing." So what's a design engineer to do? A good adage to follow is, "If it seems like too good of a deal, it probably is." But since all inferior products don't necessarily carry a low price tag, Georg Bogner, Director, Visible LED Engineering at OSRAM, stresses that engineers should be demanding their vendors to, 'Show me the data.' Poor color stability and a reduced lifetime are two key hallmarks of an inferior LED design. So at minimum, engineers should request data on luminous intensity over time and color coordinates over time. And they should try to get the data over a temperature range as well." Of course, the mere act of supplying a printed sheet of "test data" isn't a guarantee that any actual testing has been done. "Getting this data is expensive," says Bogner. "An engineer needs to make sure a potential vendor is in it for the long haul -- that they have a serious intention to design a good product and have made the appropriate investment in R&D."

Chart: Luminous intensity over time:View image

Chart: Color coordinates over time View image

Automatic doors are ubiquitous. But this product that we all pretty much take for granted represents one of the most vexing engineering exercises on the planet. The challenge: Design something that is open for a pedestrian to walk through (but only then) and otherwise closed. Detailed engineering specs have been established to help engineers cope with the complexity, but what happens out here in the real world is a whole other story.

In theory, a LED light should last for ten years or so, unlike the typical 4W incandescent lamps used in night lights that seem to burn out in only a few months. But as engineer and founder of the website Discover Circuits Dave Johnson discovered, this Chinese-made unit from Costco (apparently designed by some real dim bulbs) didn't last but 12 weeks:

"I bought a pack of three of these night lights, made by Elumina Lighting Technologies, for about $15. The unit has a pushbutton switch to toggle between settings (dim and bright) and a CdS photocell that turns off the device during the day.

Inside are three white LEDs, wired in series. When I first plugged the device in, it seemed to emit an acceptable amount of light. But in a short time, the light gradually faded until it was virtually useless.

This has happened to me several times with other inexpensive LED lights. I think some manufacturers from China are using inferior phosphors inside the LED assembly, which fatigue after only a few hundred hours. Opening the thing up, I traced out the circuit and determined it was one that I could easily modify.

I made some component value changes and pulled out the three dim LEDs and replaced them with 10 high quality, super bright surface-mounted units from Osram Opto, which I soldered together into two strips of 5 LEDs each. I paid about $1.00 each for the LEDs. So now for an extra $10 per unit (and therein lies the engineering trade-off!), the light now emits a nice bright white light and should last many years with no risk of someone taking a header down the stairs in the middle of the night!"