Friday special: Groovy Video Coat video I found on Internet:
More details on electronics can be found on Groovy Video Coat pictures and this Video Coat Prototype video:
Archive for the ‘LEDs’ Category
Video coat
Friday, September 16th, 2011Electrolytic capacitor life
Sunday, September 11th, 2011As we all know, a good LED could last very long up to 50,000 hours with with a good heat sink. But how is the LED driver electronics life? For common LED drivers there is at least one component is very weak. It’s the electrolytic capacitor.
High Bay LED Lighting Driver Heat Dissipation Temperature Test Report article gives some use useful information related to electrolytic capacitor life.
Typical temperatures for the how electrolytic caps are 85°C and 105°C. Usually the life time is 2000 or 3000 hrs at one of the above temperatures. This is how electrolytic caps are specified. But the cap’s life doubles for every 10°C below that temperature. So if you go 40°C below the specified temperature, you gain a factor of 2^4 = 16. 16× 3000 hours = 48,000 hours.
If your LED driver has caps at temperature 80 °C, the LED driver only can last about 2 years or less. After that time you can expect poor performance (lowered capacitance, increased ESR) or even capacitor exploding.
LED usage increases quickly
Friday, August 26th, 2011Lighting apps boost LED usage article says that in in 2011, DisplaySearch predicts global LED capacity will reach 180 billion units, and by 2013 will reach 227 billion. The total average LED penetration in lighting was 1.4% in 2010 and is forecast to reach 9.3% in 2014.
LEDs and dimmers
Thursday, April 14th, 2011Using existing triac controllers and wiring offers a number of challenges for LED lighting. To maximize the success and adoption of solid-state lighting for retrofit lamps, the LED lamps should be capable of dimming when used with existing controllers and wiring.
Lighting designs with flicker-free LED dimming article explores the typical TRIAC dimmer, some of the challenges of using it with LED lighting, and two interesting new power management solutions that solve these issues.
A common lighting dimmer available today is the leading-edge TRIAC dimmer. For an LED lamp to be dimmable, the lamp’s power supply must interpret the variable phase angle output from the TRIAC controller to monotonically adjust the constant current drive.
The difficulty of achieving this while keeping the dimmer working correctly may result in flickering, audible noise, and blinking as the light level is adjusted. These are generally caused by a combination of false triggering or premature shutdown of the TRIAC and inadequate control of the LED current. For reliable dimming down to low levels, the TRIAC must remain conducting almost to the point where the AC voltage falls to zero.
LEDs Deliver More from Less in Car
Thursday, February 3rd, 2011LEDs Deliver More from Less article tells that LEDs continue to penetrate automotive lighting applications due to their long life and design flexibility.
LEDs continue to penetrate automotive lighting applications due to their long life and flexibility of use for body styling and interior design. LED lighting, used for the headlights, daytime running lights and turn signal indicators, allow for much greater design flexibility than that of either Xenon or incandescent light bulbs. This permits the body designers of an automobiles front end to do things that they could never do before.
The headlight itself has been the elusive goal of LED adoption in an automotive environment. The main reason for this has been the thermal design aspects of the LEDs and their associated driver circuits.
A high power, or high brightness LED’s light output has already exceeded the critical milestone of 100 lumens per Watt (lm/W) (15 lm/W for a typical 60W bulb).
LEDs Deliver More from Less article shows how a 25W white LED headlamp can be configured using an array of 18 LEDs in series with 350mA of current passing through them to produce the necessary light output. This kind of configuration can really live up to their promises and be effective headlamp.
Same can’t be said on the drop-on replacement products for normal light bulbs. My earlier LED car lights article shows how they do not live up to their promises and do not meet the regulations on car lights.
So if you want to have LED headlight on your car you need to have a new headlight design specifically designed for LEDs in mind.
Communicating LED lamps
Friday, January 7th, 2011LEDs are used for a long time for all kinds of data communications applications ranging from wireless IR remote controls and IrDA to wired fiber optics communication. There has been many years ago also ideas on optical wireless LANs based on infrared, but they faded quickly. But now when LED lights are becoming very popular this idea could see a second coming.
Ceiling lights in Minn. send coded Internet data article tells about LED lights that will transmit data to specially equipped computers on desks below by flickering faster than the eye can see. The first few light fixtures built by LVX System will be installed in six municipal buildings in the central Minnesota. The LVX system puts clusters of its light-emitting diodes in a standard-sized light fixture. The LEDs transmit coded messages A light on the modem talks back to the fixture overhead, where there is sensor to receive the return signal and transmit the data over the Internet. It works in almost exactly the same way that fiber optic systems do, except the sender and receiver aren’t connected by a cable. Communicating lights are set up using just ordinary power connections. The first generation of the LVX system will transmit data at speeds of about 3 megabits per second. If you are interested check video from Get ElectricTV.
There is another application that also combines wireless communications and LED lights. Finnish article Wlan ohjaa yksittäisiä led-loisteputkia (read English translation) tells about LED light tubes can be controlled by a WLAN connection, even individually. Finnish company Valtavalo has licensed Netled control technology from Yashima Dengyo Co., Ltd. and sells their products. Netled technology is designed to provide means to monitor in electricity consumption in real time and control the various LED light tube groups.
Lamp vs LED power
Tuesday, January 4th, 2011When visiting Motonet show one day I saw LED light bubs display with following match for LED bulb power to classic light bulb watts (similar idea as in energy saving lamps matches certain watts normal bulb). The power ratings I saw was: 1.3W LED would match 13W normal bulb. And 2W LED would match 20W bulb. And so on.
Sound like about right as general rule of thumb for LED products now. But keep in mind that the efficiency of LED bulbs vary considerably depending on how light bulb is built and what components are used in it (and products will continue to change over years). One example is that a 7W LED bulb (at 560 lumens) can serve as a replacement for a typical 500-lumen 40W incandescent bulb.
I have earlier written about LED car bulbs. A 55w halogen should typically be putting out 500 to over 1000 lumens. A good 3.4w led would be about 250 or less. So something like 3-4 of such LEDs would be needed to the same output as 55w halogen gives out.
The Great Internet Light Bulb Book says about light bulb lumens:
In a 120 volt, 100 watt “standard” bulb with a rated light output of 1750 lumens, the efficiency is 17.5 lumens per watt. This compares poorly to an “ideal” of 242.5 lumens per watt for one idealized type of white light, or 683 lumens per watt ideally for the yellowish-green wavelength of light that the human eye is most sensitive to.
Most household incandescent bulbs have efficiencies from 8 to 21 lumens per watt. The reason for this poor efficiency is the fact that tungsten filaments radiate mostly infrared radiation at any temperature that they can withstand. Higher efficiencies near 35 lumens per watt are only achieved with photographic and projection lamps with very high filament temperatures and short lifetimes of a few hours to around 40 hours.
Accurately simulate an LED
Wednesday, October 20th, 2010Solid-state-lighting applications are quickly moving into the mainstream. Testing the driver circuit using LEDs, although easy, yields only typical results. Accurately simulate an LED article shows a circuit that you can use to test your LED drive circuit with worst-case LED parameters. You can easily tune this one transistor test circuit for any LED voltage. Looks useful. And quite simple.
LED lighting teardowns
Monday, October 11th, 2010LED-based lighting is still far from a mainstream technology, and its designs are in flux. Early SSL products are making their way onto store shelves and into inventory. LED lighting teardowns: Five lighting designs that illuminate the future of lighting article shows product examples that can indicate what direction SSL design will take, at least in its early stages.
LED lamp lifetime
Monday, September 27th, 2010LED light manufacturers are often claiming 50,000 hours or more for lighting lifetime. Unfortunately many times those lifetime expectations are not met. Usually the makers of those high those lifetime promises forget to include the lifetime and reliability of all components, and the real-world thermal conditions the LEDs are subjected too.
Just a few years ago, LEDs operated at such low power that they didn’t need any special cooling. But as LEDs have grown brighter and more powerful, thermal management has rapidly becoming a necessity. Designers need to understand that accurate thermal modeling as well as component selection will ensure their lighting designs meet their reliability and lifetime numbers.
