By Steven Keeping:
Until recently, a lighting designer looking to take advantage of the efficacy, longevity, and robustness of LEDs for his/her next luminaire was faced with some key challenges.
Among the toughest of these was the need to work out how many discrete LEDs were required to achieve the required “lumen density” (light output per unit area) for the product, and then design a circuit board that took into account the power- and thermal-requirements of this array without consuming too much space inside the lamp. Then the engineer needed to make sure that all of the LEDs in the group produced an identical color to meet the consumers’ expectations.
Today, a simpler solution is at hand. LED makers have introduced a new form of packaging for their high-power devices: the chip-on-board (COB) LED array. In supplying these units, the LED maker has done the work of matching the individual LEDs and designing a suitable substrate to carry the “light engine.” Better yet, COB LED arrays allow LED makers to take advantage of efficiency-enhancing techniques such as “remote phosphor”.
This article reviews the latest commercially available examples of COB LED arrays and considers how the sector will develop in the near future.
The Rise of Chip-on-Board LED Modules - [Link]
Syst3mX @ instructables writes:
One day I was sitting behind my desk at work and I got that weird need to build something, after looking around for a bit I got my eye on an LED matrix and that sparked an idea in my head : “I WANNA MAKE A TAMAGOTCHI”.
So for those of you that don’t know what the heck is a Tamagotchi here is a little snip-it from wikipedia :
“The Tamagotchi (たまごっち Tamagocchi?) is a handheld digital pet, created in Japan by Akihiro Yokoi of WiZ and Aki Maita of Bandai. It was first sold by Bandai in 1996 in Japan.”
So my take on this classic toy is to make it in to a desktop gadget with an LED matrix for a display, and an Arduino for brains to make it more accessible to people. With that said join me as we design,build and program the World’s first (As far as I know) desktop Tamagotchi.
Make a Desktop Tamagotchi - [Link]
hardwarehank @ instructables.com writes:
The Atmel ATTiny85 chip is an 8-pin MCU that is totally awesome. If you’ve been programming with the bigger boys (the ATMega series), these are a nice adventure – you’re rather limited in the number of output pins, but a creative design gives us a lot of flexibility in a very small package.
You’ve seen them – those “Apple computers.” Probably in the hands of some Hipster in Portland, while riding his fixie and wearing those thick framed glasses. That pulsating light when Apple laptops are asleep is so … sooooothing. You just want to go to sleep watching it. You know you do.
Today, we’re going to replicate that using our ATTiny85. It’s really easy, and most of it can be implemented in hardware instead of code (!!!).
Apple-style LED pulsing using a $1.30 MCU - [Link]
xlisus @ instructables.com writes:
Choose the hue of light that makes you feel more comfortable.
Simple bluetooth remote control from which you can modify lighting from your mobile device or tablet.
- You have two separate RGB channels where you can get different colors per channel.
- Control adjustable intensity.
- Do it yourself .
- Thanks to the arduino platform in minutes you ‘ll Omniblug armed and ready for use.
Discover all the features provided. Is very easy install this small device.
Android Bluetooth Control Led RGB - [Link]
To satisfy electronic DIY hobbyists, ICStation has developed MAX7219 Dot Matrix Module. It uses the Max7219 chip which do a great job on saving of MCU I/O. It can not only control each point individually, but also can be extended without limitation to meet your requirements on LED Sign, Team Logo and so on.
What’s more, it’s controlled by the STM8S003F3 MCU with 1K data storge space which is low cost, low power consumption, very powerful.
DIY LED Sign with MAX7219 Dot Matrix Module - [Link]
This GU10 LED spot light is cheap (£3 including postage) and bright. But it’s also lethal! There’s a 50% chance of putting live mains within a few microns of the metal casing (which is what you’ll be holding when you insert it) and there’s no earth to protect you. It’s like playing Russian Roulette with 240v AC mains. This sort of thing gives new technology a bad name. Avoid it if you want to stay alive.
Dangerous GU10 LED Spot Light is Cheap and Bright but could Kill You – Seriously - [Link]
Julian Ilett writes:
I discovered that due to a lucky co-incidence of voltage and internal resistance, a 100W LED can be connected directly across the terminals of two 18V Nickel Cadmium power tool batteries. And that means you can build a 100 Watt (7,500 Lumens) flashlight for less than $10 (not including batteries).
Monster 7,500 Lumens 100W LED Flashlight for under $10 - [Link]
frankenroc @ instructables.com writes:
You don’t have to be in Times Square to enjoy large bright displays of lights. You can create that in the comfort of your own home with some foam board, LEDs, and our little friend Arduino.
My sister-in-law decided to get married on New Year Eve, and the venue she chose stays open until 1am that night, so I started thinking it would be great to have a nice big countdown clock. I ran the idea past her and her fiance and they both loved it, so I went to work.
When I made it I intended it for just one use, but it’s a very impressive display that can be seen across a huge room. This is pretty simplified and what I’m showing you is on a breadboard. Optimizing and taking it beyond prototyping (e.g. replacing the breadboard with some pcb boards) are outside of the scope for this but shouldn’t be too difficult.
Giant Two-Digit Countdown Clock - [Link]
High color fidelity approaching an ideal is a common feature of „high CRI“ Osram LEDs with CRI up to 96.
When you recall to lessons of physics from your basic- or grammar-school, probably you´ve heard a term „black body radiation”. As we know, each object with a given temperature radiates in a wide range of wave lengths, while a maximum of a radiation depends on its temperature. We mention it because the Sun also operates on this “principle” and its spectrum (light) depends mainly on its surface temperature. Temperature of an object is also the most important factor influencing whether the light will be “warm” or “cold”, that´s why a term color (chromacity) temperature CCT is used.
Even though a portion of radiation (some wave lengths) is absorbed in atmosphere, it can be said that it is very near to a black body spectrum and it´s ideal for us in respect to a pleasant and true color perception.
There are several methods to evaluate color fidelity and one of the most important is so called CRI (color rendition index, maximum = 100). To an ideal light source with CRI =100 is very near a classic incandescent bulb, even though it´s spectrum is shifted towards warmer tones. Unfortunately a light spectrum gained from hot surfzce object also contains a large portion of thermal (infrared) radiation, what causes a low efficiency of incandescent bulbs. However LEDs deploy emission of photons on an other principle (change of electrons energy), so their surface is in fact “cold” in comparison to what temperature a black body radiator should have to gain a similar spectrum.
Modern LEDs have a high CRI, usually over 70. But among LEDs we can find types with even higher CRI (above 80) , as well as “color champions” with even higher CRI. To such champions also belong LEDs from the OSLON Square series, which we introduced to you in our article New LED OSRAM OSLON Square withstands up to 1.5A. Since then company Osram advanced in development and was able to make types with a typical CRI 96 (!), for example LCWCQAR.CC-MPMR-5J7K-1 (4500K).
Light fidelity of this LED is extremely high and such light is very suitable for lighting of areas with high requirements for a light quality, like for example: galleries, museums, shops, photographic ateliers as well as for an everyday work. Despite a high CRI, this particular type also features a considerable efficiency of 180-224 lm/700 mA and a max. current up to 1500 mA.
Among novelties from company Osram can also be found the Oslon Square 2nd generation with even betterthermal features increasing lifetime and efficiency at high temperatures. Moreover this new 2-nd version is sorted (binning) at 85°C, what ensures minimum color in a real operation.
Almost perfect light from the Oslon Square LED - [Link]
Lee Zhi Xian writes:
I was always fascinated with LED Matrix Display because it makes a good and clear display. I always saw LED display used as advertisement signboard. It can be programmed with variety of animations. So I decided to make myself a 48×8 LED Matrix Display. Of course, I start off with a smaller one by soldering LEDs on stripboard, making a 8×8 LED Matrix. I tried to understand how the LED Matrix works and how to deal with the programming part.
Development of 48×8 Led Matrix Display - [Link]