On things about which I have an opinion
My kitchen has had halogen lighting for 20 years, from back when it was a slightly more efficient choice than incandescent lighting and had a pleasing, cooler (bluer, meaning the filament runs hotter) color temperature.
Progress has moved on and while fluorescent lights still have a lead in maximum luminous efficacy (lm/w), for example the GE Ecolux Watt-Miser puts out 111 lm/W, they’re less versatile than LEDs and installation is a hassle while low voltage LEDs are easy to install and look cool.
The goal of this project was to add dimmable, pleasing light to the kitchen that I found aesthetically interesting. I wanted a decent color rendering index (CRI), ease of installation, and at reasonable cost. I’ve always liked the look of cable lighting and the flexibility of the individual, adjustable luminaires.
I couldn’t find much information on how variable output LEDs work and what can be used to drive them. I have a pretty good collection of high quality power supplies, which I wanted to take advantage of, but wasn’t sure if I’d be able to effectively dim the bulbs from the documentation I found. So I did some tests.
I bought a few different 12V, Dimmable LEDs and set up a test configuration to verify operation and output with variable voltage and variable current. The one bit of data I had was that using standard commercial controllers, the lowest output is typically stated to be around 70% of maximum output: that is the dimming range is pretty limited with standard (PWM/Transformer) controllers. The results I found were much more encouraging, but revealed some quirks.
I used a laboratory-grade HP power supply with voltage and current control to drive the LEDs, decent multimeters to measure voltage and current, and an inexpensive luminance meter to measure LED output.
I measured 3 different LEDs I selected based on price and expected compatibility with the aesthetics of the project and because they looked like they’d have different internal drivers and covered a range of rated wattage.
These bulbs have internal LED controllers that do some sort of current regulation for the diodes that results in a weird voltage/current/output response. Each bulb has a different turn-on voltage, then responds fairly predictably to increasing input voltage with increasing output, reaches the controller stabilizing voltage and runs very inefficiently until voltage gets over the rated voltage and then becomes increasingly efficient until, presumably, at some point the controller burns out. I find that the bulbs all run more efficiently at 14V than at the rated 12V.
As a side note, to perform the data analysis, I used the excellent
xongrid plugin for excel to perform Kriging interpolation (AKA Gaussian process regression) to fit the data sets to the graphing function’s capabilities. The graphs are generated with WP-Charts and the table with TablePress.
Watts v. Volts
This chart shows the wattage consumed by each of the three LEDs as a function of input voltage, clearly demonstrating both that the power consumption function is non-linear and that power consumption in watts improves when driven over the rated 12V. Watts are calculated as the product of the measured Volts * Amps. Because of the current inversion that happens as the controllers come fully on-line, these LEDs can’t be properly controlled near full brightness with a current-controlled power supply, though it works well to provide continuous and fairly linear dimming at low outputs, once the voltage/current function changes slope, the current limiting controller in the power supply freaks out.
4W LED 5W LED 7.5W LED
Lux v. Volts
This chart shows the lux output by each of the three LEDs as a function of input voltage, revealing the effect of the internal LED driver coming on line and regulating output, which complicates controlling brightness but protects the LEDs. The 5W LEDs have a fairly gentle response slope and start a very low voltage (2V) so are a good choice for a linear power supply. The 4W LEDs don’t begin to light up until just over 6V, and so are a good match for low-cost switch mode supplies that don’t go to zero.
4W LED 5W LED 7.5W LED
Lux/W v. Volts
This chart shows the luminous efficiency (Lux/Watt, Lumen measurement is quite complicated) by each of the three LEDs as a function of input voltage, showing that overdriving the LEDs past the rated 12V can significantly improve efficiency. There’s some risk it will overheat the controller at some point and result in failure. I’ll update this post if my system starts to fry LEDs, but my guess is that 14V, which cuts the power load by 20% over 12V operation with the 7.5W lamps I selected, will not significantly impact operational lifetime.
4W LED 5W LED 7.5W LED
Total System Efficiency
The emitter efficiency is relatively objective, but the total system efficiency includes the power supply. I used a Daiwa SS-330W switching power supply I happened to have in stock to drive the system, which cost less than a dimmable transformer and matching controller, and should be significantly higher quality. The Daiwa doesn’t seem to be easily available any more, but something like this would work well for up to 5A total load and something like this would handle as many as 40 7.5W LEDs on a single control, though the minimum 9V output has to be matched to LEDs to get satisfactory dimming. It is important not to oversize the power supply too much as switch mode supplies are only really efficient as you get close to their
With the Daiwa, driving 13 7.5W LEDs, I measured 8.46A at 11.94V output or 101 Watts to brightly illuminate the entire kitchen, and providing far more light than 400W of total halogen lights. I measured the input into the power supply at 0.940A at 121.3V or 114 Watts. That means the power supply is 88.6% efficient at 12V, which is more or less as expected for a variable output supply.
Increasing the output voltage to 14.63 Volts lowered the output current to 5.35A or 78 Watts without lowering the brightness at the installation (measured at 168 lux at both 12.0V at 14.6V). The input current at 14.63V dropped to 0.755A or 91.6 Watts, meaning the power supply is slightly less efficient at lower output currents (as is usually the case).
- Overdriving the LEDs to 14.63V improves efficiency by 20%.
At the low end, the SS-330W’s minimum output is 4.88V, which yields 12 lux at the counter or a 14x dimming ratio to 7% of maximum illumination, a far better range than is reported for standard dimmer/transformer combinations.
- 7.5W LED modules from JackyLED
- Daiwa power supply (alternate version)
- 16 gauge speaker cable
- MR-16 cable lamp mounts
- Digital light meter
(MS Excel file, you will need the
xongrid plugin to update the data as rendered in the graphs)
I’ve run across this energy drink in dramatic packaging. Energy drinks aren’t really my thing, but I thought I’d try it: slightly orange tasting fizzy water, mildly sweet with that slightly weird energy drink taste. But the bottle is fun:
It is made in Hungary and seems to be distributed more to the East than the West, at least as far as my travels have indicated. I have seen it in a lot of Middle-Eastern markets, but not in many European ones.
The lid release mechanism is kind of thematically clever.
I suspect this would be a particularly problematic beverage to forget in your carry-on luggage.
There are two things I always do with a new digital device, get a good screen protector and a good case. (And the biggest memory card that will fit).
The screen protector is pretty easy: I’ve used both Zagg and Armor Suit and prefer the Armor Suit, but not by much. Both work really well and I have an Armor Suit on my Motorola Razr V9x (still the best basic cell phone I’ve ever owned) that has lived in my pocket for many, many years without a scratch visible on the outer screen.
For cases I lived with an (almost iconic) yellow Defender case for my Blackberry Bold 9000 for about 5 years. It was awesome, indestructible, and fit the belt holder perfectly. Alas, it was no match for a random late night cab ride and early flight out of Dubai–can’t defend against that, can ya? Well, it lasted about 5 years, so no complaints. I contacted Otterbox to see if I could get a replacement silicone bit and they checked and only had 2 belt holsters left in stock from the entire product line. They mailed me those for free. Thanks Otterbox! (One did come in handy eventually.)
I got an iPod from United and, of course, got an Otterbox for it; one of the Commuter series. With a polycarbonate outer shell protecting the critical corners, and that backed underneath by a few mm of soft silicone, the iPod is extremely well protected. This is a well-engineered protection model, far better than just a layer of silicone.
A corner drop tends to generate very high localized pressure where the corner tries to merge with the hard surface it is being dropped on. Having the polycarbonate outer shell distributes that pressure load over the silicone underneath it resulting in a broad, gentile distribution of the impact load and minimizing the risk of localized overpressure which would crack plastic or glass.
Conversely, simple silicone sleeves without the polycarbonate layer, while adding critical padding and being fairly effective in most cases, can’t distribute the impact load nearly so effectively. This should not matter too much for a surface-to-surface drop where the impact force is distributed over the whole back or even an edge of the phone, but in a corner drop the silicone can be effectively mushed out of the way as the hard surface attempts touch delicate plastic or glass in a tragic romance.
I replaced the Blackberry with a Samsung Galaxy S3 and got a Commuter case for it. The case is very nice, not too big, but Otterbox did something very, very wrong. They rotated the polycarbonate tabs 45 degrees, covering the edges and not the corners. Why Otter, why? The case is still quite nice and it is the nicest looking and most comfortable I’ve found, but this is an odd engineering mistake. They talk about the “layers of protection” as a key selling point for their more expensive Commuter and Defender series, yet leave the most fragile corners protected by only a single layer. As protection goes, it is no better than the Impact since the corners are all that really matters.
The polycarbonate shell does serve to anchor the access flaps closed, which is an improvement over the iPod case, but this could easily have been achieved with a few well-placed polycarbonate fingers reaching around the case without making it difficult to assemble (too many fingers wrapping around the device make it impossible to snap the device into the polycarbonate shell).
Further, the textured silicone edges on the iPod case are actually really nice to hold, far more comfortable and slip-resistant than the polycarbonate edges of the S3 case (and make the iPod less likely to drop than the S3 as well). As an additional bonus, the iPod version exposes some textured silicone on the back surface making the case somewhat non-slip, while the S3 case is all polycarbonate on the back. Without some non-slip silicone on the back, the likelihood that the enclosed device will slip off a sloped surface and onto a hard floor or into a toilet or sink is much greater. While the case makes a disaster far less likely for the former eventuality, it is not waterproof.
While the Android OS just crushes iOS, and the availability of Android-specific tools and applications, particularly for security and encryption, makes it the best choice for a mobile device right now (though security, at least, is even less of a concern with a Blackberry – that’s the one thing Rim still has going for it – that and efficient use of data), Otterbox really could have done a better job with the case. Hopefully the S4 case will get it right.
It has been almost 2 years and I’ve been carrying the Otterbox-protected S3 more or less continuously since in a relatively active and somewhat unforgiving environment, not that anyone’s pocket or purse would fail to meet that definition. A few issues emerged:
- The rubber flap covering the USB port, which you need to access at least twice a day for charging, tore off very early on;
- I change SIMS a few times a month and the case doesn’t really like being taken on and off and eventually cracked in two places, but it still holds together;
- The unprotected silicone covering the corners began to deteriorate fairly quickly, as I predicted, and one corner has disintegrated completely, leaving that most fragile of impact points unprotected.
I’d probably buy another – two years is a pretty good life (but not as good as the 5 my blackberry gave me. I still miss that phone). I wish Otterbox would focus on protecting the corners, not the edges. The iPod case, far less heavily used but equally traveled shows no wear on the corners at all and provides the same protection it did two years ago. It is a better design.
I learned two things about Futurama recently which added to my already deep appreciation for the show. The first is that the theme song came from a very cool song by Pierre Henry called Psyche Rock from 1967, which is on youtube. It was remixed by Fatboy Slim in an appealing way.
But what was most interesting recently was to see episode 10 of season 6, the Prisoner of Benda, a spoof of the Prisoner of Zelda but including what may be the first tv-episode publication of the proof of a relatively complex mathematical theorem in group theory as a core plot element.
The problem in the plot is that the Professor’s mind swapping machine creates an immune response which prevents swapping back in one step. So how do you get everyone back to into their original bodies? Well, as Sweet Clyde says, it takes at most two extra players [who haven’t swapped yet]. As the entire cast, including the robo-bucket, have swapped bodies, the situation is pretty complex, but fortunately one of the show’s writers, Ken Keeler, has a PhD in applied mathematics from Harvard and found a proof, which is actually shown in the show (above), and then worked in a fast montage that restores everyone.
In the following table, the heading shows the character name of the body, row 0 shows the occupant of that body by the end of the plot’s permutations and before the globetrotters start the transformations. Rows 1-7 show the steps to restore everyone to their original bodies. Each transformation was animated as a pair using the two “extra players” except the last rotation to restore Sweet Clyde and the Bucket.
What happened to 1920×1200 laptop displays? Why are all new laptops regressing to 1920×1080? That’s the most asinine, disappointing regression since the end of commercial supersonic transport. It is so sad to be living in a world that is moving backwards at an ever accelerating pace.
My first transportable computer was a Mac Portable with a 640×480 screen and I lived with that through a couple of generations. Eventually I got a Dell with 1440×900 pixels and could actually do some real work on it. About 10 years ago I got a Dell M70 with 1900×1200 pixels on a 15.4″ screen and found an acceptable resolution for portable work. Little did I know that the era from about 2000-2010 would be the apex of laptop technology. It is all downhill from here.
Once I looked forward to a bright future with 17″ displays sporting about the same generally usable pixel pitch (about 147 pixels per inch). If the world had continued to advance technically, if the now retired SR71 wasn’t still the fastest, highest flying plane ever built, if the now retired Concorde wasn’t the only commercial supersonic aircraft, if the retirement of the space shuttle didn’t herald the end of US’s manned space flight capability, if we weren’t living on the burnt out ruins of our former capabilities watching our technical competency spiral down the toilet, we’d have WQXGA (2560×1600) 17.4″ laptops right now. Maybe even QXGA 15.4″ options for those of us with good eyes.
But we don’t. We have bizarre stupid Vaio VGN-AW11M/H with kid friendly 104 PPI displays sporting useless 1680×945 pixels on an 18.4″ screen. That’s a pixel pitch straight out of 1990. Thanks for nothing.
Nobody even makes a reasonably sized laptop with a 15.4″ screen with more than 1920×1080 pixels any more (the only WUXGA laptop I can find at any size is the oversized kidz pitch 17″ macbook pro). I’m going to have to stick with my W500, or buy used ones for the rest of my life. Laptop makers – there’s no way I’m going to regress to a less productive smaller pixel count. That’s just stupid. Pull your heads out and give us pixels. The only thing that really matters for productivity is pixels. More pixels=better. Less pixels=worse. Don’t bother releasing a new laptop if it is worse. If you’ve lost the competency, just pack it up.
Apple: the 264 PPI pitch of the 3rd gen ipad is pretty good. If you build a 15.4″ macbook pro with that pitch in QFHD (3840×2160) pixels instead of the bizarrely large type kid’s book useless 1440×900 pixel resolution the current 15″ macbook pro is crippled by, I would actually buy one to run Ubuntu on. And maybe even have a bit of hope for the future.
(I’d suggest refraining from buying a laptop until 2013: ivy bridge will make 1920×1080 laptops as quaint as those 640×480 displays from 1990: the era from 2010-2013 may be known as the dark ages of laptops.)
Megaupload, the company that enables easy file transfer used by 50,000,000 people every day, was sized by the DOJ. Check www.megaupload.com
This is an illegal, unconstitutional seizure. It is an example of the scum who run entertainment companies like Universal (who illegally got MegaUpload’s video yanked from youtube by filing a false DMCA takedown) turning US law enforcement and the US judicial system into criminal enforcers to create a business model around theft and intimidation to replace their obsolete and irrelevant role as gate keepers and toll collectors between artists and their audiences.
If SOPA/PIPA pass, links to the sized domain would have to be expunged from any site even talking about them. This is intolerable. It is a subversion of democracy and outright theft of the public domain by those who would retard or even reverse progress to protect their profits and wealth.
The constitution grants the privilege of a temporary copyright to artists and inventors as a mechanism to promote the progress of science and the useful arts. Laws that extend this privilege in a manner that fails to promote the progress of science and the useful arts are plainly unconstitutional. Record companies have no natural right to stop you from using your hardware, your devices, to rearrange the bits on your systems in any way you like. They have turned the discussion to claim they have a property right to your data through manipulation and outright lies. The only fair response to their illegal and heinous acts is to revoke their privilege and drive them swiftly into bankruptcy so they no longer have the resources to bribe our representatives into ignoring the constitution.
The DOJ should be using RICO to shut down entertainment companies that use intimidation to protect profits, not innovative companies acting to expand the public domain in a manner clearly consistent with the goals of the framers of the constitution.
It has two defining features:
- it is a convertible and a sporty one at that,
- it comes with a subwoofer equipped stereo which defines the target market.
This is definitely not a car targeted at classical music listeners. The stereo with the fosgate “punch” setting cranked up is a base heavy “boom car” experience. It sounds fine, the base is clean and well rendered, but it isn’t the balanced, well staged clarity of the sound system in a Mercedes, for example, but fits a particular demographic well.
The car itself is quite sporty and handles well. Unlike a lot of lower end convertibles, including the Mustang, the body is very stiff and and takes turns and bumps without any tangible body flex. The car corners flat and understeers predictably and with good control (I discovered unintentionally while making a quick u-turn). The car also has more power than one would expect for such a small vehicle, and can spin the back wheels from a stop without resorting to a neutral drop, also an unintentional discovery. Really.
Road noise with the top up is pretty good for a convertible, and better than most at freeway speeds with the top down.
I’d say it is a pretty good choice for a low cost, youth-oriented convertible.