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Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen

Kevinc

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Kevin Chen

Kevin is Product Manager of Lumex in Asia-Pacific region, responsible for product development and technical support. Kevin joined Lumex in 2007, accumulated experience in LED/LCD technology, assistance for numerous clients to solve their problems on technology and cost, providing creative and smart solution with diverse service. Kevin is recognized for LED / LCD technology experience, ability to solve complex design challenges from customer and project management capability, with different aspects to simplify the design, enhance reliability, energy-saving orientation and ease of maintenance. Thinking from the origin of the design, implement the concept of energy saving, environmental protection and health into product, providing green lighting solutions for customers to reduce costs and improve efficiency.


  • 1. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    matts

    Kevin,

     

    I want to install 24v led lights in my kitchen cabinets.  I want the lights to turn off and on when I open and shut the cabinet doors and drawers.  I need 35 or 40 switches, so I would prefer a lower cost switch.  But I would prefer a proximity switch, if there was a small one.  I would be ok with considering a limit switch or a plunger style switch.

     

    What style switch would you use?  The drawers could be any switch since I could hide it in the cabinet. But the doors I would prefer to keep a small diameter hole for the switch to stick through or if possible a proximity switch so maybe I could drill a blind hole so the switch would not be seen.  I could french in a metal slug into the cabinet door if it was cheeper to use a maginet style proximity switch.

     

    Thanks

    Matt Spawn

  • 2. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    amacrine12

    i would like to light a rectangluar box of about 18'' by 36'' inches to a level of 5 milliwats per square cm, using an led array if possible, can you suggest a lighting system from Newark to do this?

    thanks

    John

  • 3. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    Kevinc

    Dear Matt:

     

    Your "maginet style proximity switch" is a good choice. Proximity switch is a kind of limit switch. You can refer to this link: http://en.wikipedia.org/wiki/Limit_switch

     

    In general, the common switchs will be ok, it just the mechanism to do ON/OFF operation. However, you must be aware of your LED operating current/voltage, there is a component, called "current limiting resistor", if you want to build up your LED lighting circuit,

    Your LED light may have it, but I suggest you to double check, just in case.

     

    Here is the link for your reference.

    http://en.wikipedia.org/wiki/LED_circuit

     

    Have fun!

    Kevin

  • 4. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    Kevinc

    Dear John:

     

    5W/ft should be enough for your.

    Suggested this link:

    http://tw.element14.com/jsp/search/productListing.jsp?SKUS=2078127,2078128,2078129,2078130,2078131,2078133,2078134,2078135,2078136,2078137,2093894,2078124,2078125,2078126,2078138

     

    SSP-LB12UW024K05  for cool white,

    SSP-LB12NW024K05  for neutral white

    SSP-LB12MW024K05 for warm white,

     

    Hopes this can help you.

    Kevin

  • 5. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    Ganesh1

    Hello Kevin,

     

    I'm Ganesh from India, and i have few questions regards to LED.

     

    1. What is least cost of LED? I mean pricing starts from
    2. What is meant by Bin in LED? Elaborate clearly
    3. What are the main technical aspects required? While selecting a LED for design
    4. Define difference between Dominant and Peak wavelength
    5. Define viewing angle, Interms of viewing angle( Less viewing angle is good or Large viewing angle is good)
    6. What is meant my diffused and clear?

     

    Regards,

    Ganesh Shetty

  • 6. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    aa9dt

    Kevin,

     

    I want to know how to match LEDs with different viewing angles. For example, say that I have an LED with a viewing angle of  20 degrees. I want to approximately match this viewing angle to a group of 10-degree LEDs. Could I achieve a 20-degree viewing angle with four 10-degree LEDs (two rows of two)?

     

    Would the brightness be roughly the same as the brightness of the 20-degree LED?

     

    Thanks,

     

    James

  • 7. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    Kevinc

    Hi, Ganesh Shetty

     

        1. What is least cost of LED? I mean pricing starts from

    Re: It's hard to tell you the least cost. It will depend on performance/ quality/ volume demand. You need to determined those factor, then define the cost range you requied.

     

        2, What is meant by Bin in LED? Elaborate clearly

    Re: BIN is the classification of LED after testing. While LED was made as completed products, LED testing will sort LEDs by Brightness/ Forward voltage/ Wavelength by constant current based on

          LED datasheet ( in general, the If is 20mA).

          Take an example, if LED's voltage range is 2.0-2.6V, Forward voltage will be devided as 3  BINs ( like sections), 2.0-2.0V, 2.2-2.4V, 2.4-2.6V.

          If wave length could be devided as 2 BINs, and brightness as 4 BINs.

          The total BINs will be 3*2*4 = 24BINs.

     

        3. What are the main technical aspects required? While selecting a LED for design

    Re: If pricing and leadtime is not the item we talk about, here is the aspects for me:

          1. Your application will determine what kind of LED you need, fistly, the appearance of LED, like through hole LED/ Surface mount LED/ LED displays/ LED indicator/ light bar..

          2. Color: That is wavelength. How many pcs you will use on your module? If you use more than 2 pcs of LEDs on your PCB and side by side, BINNING will be important.

          3. Intensity: that is brightness.

          4. Voltage and Current.

          5. Reliability

     

       4. Define difference between Dominant and Peak wavelength

    Re: Dominant wavelength is the color which human eye sensed and corresponded to the single wavelength in CIE color coordinate space.

          http://en.wikipedia.org/wiki/Dominant_wavelength

          Peak wavelength is the wavelength which are measured under the maximum intensity.

          You can said that Peak wavelength is the color machine sensed, and Dominant wavelength is the color human sensed.

     

       5. Define viewing angle, Interms of viewing angle( Less viewing angle is good or Large viewing angle is good)

    Re: LEDs are measured so that the line along half the viewing-angle from directly forward is half the brightness as at directly forward.

          If used 2 LED ships with the same intensity to package 2 LED lamp, the brightness of  lamp with less viewing angle will be brighter than large view angle.

     

       6. What is meant my diffused and clear?

    Re:Diffusd means the lens is fogged. Clear means the lens is transparent.

  • 8. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    Kevinc

    Hi, James:

     

    You have 2 ways to achieve your target:

     

    1. To find another LED, you just use only one with the higher brightness and the viewing angle you specify.

    2. If you still need 2x2 LED cluster. You will need someone to do "secondary optics" design for you, to achieve the viewing angle you specify.

       You can search the keyword of "secondary optics" on websites.

     

    Kevin

  • 9. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    DavidBardes

    Hey Kevin,

    Greatings from North Carolina, USA.  I am building custom LED lamps using 3W RGB diodes and an RGB controller that is common on the market. It has a 44 key IR remote controller and a 4-pin RGB cable coming out of the contoller.  The device is 12v rated at 72watts with 2A per channel for a total of 6A.  I am testing it with 16 3W RGB bulbs and I have blocking diodes and 2.2ohm 150W wire round resistors. 

     

    THe problem is that I keep blowing the RGB contoller. Inside, at the wire junctions is a transitor that gets too hot and blows.  I don't think the logic on the controller is very well planned as if I use a volt meter accross any of the channels, it blows the contoller.  I thought it might me too much foward or reverse current going back to the controller to blow it. THe blocking diodes seemed to work, and the big resistor's seem to carry the load without getting too hot. THe contoller is designed for those strip LED lights, so perhaps I am missing something.

     

    Would you have any suggestions as to making my circut stable? Am I missing something?  Thank you so much for any help you can provide.

    Best regards,

    David Bardes

  • 10. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    jcollege

    I have been introduced to super-luminous LED's. Is there a difference? Also, what colors offer healing, and in what areas?

  • 11. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    prilinger

    I saw this link which was an interesting explanation of super luminous led.

     

    http://www.spectramedics.com/index.php?id=91

     

    Phil - Newark Tech Support

  • 12. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    jcollege

    Thanx! Now I'm looking for a good company to get a reasonably priced system

     

     

     

    John

    770.617.0984(c)

     

     

    >

  • 13. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    skywardsword

    Hi Kevin,

     

    I am Tan(Chen) from Malaysia. I have about 30 plus unit of LED downlight lamps, with 4 Cree XPE led, rated power 8w, power factor >0.9, input voltage 100-240VAC that started to flicker non-stop. At first I suspected maybe the caps on it may have expired. I dismantled the lamp to visually inspect it. The caps does not seem to have any sign of bloating/corrossion or problems that I could pin it on.

     

    So I am thinking maybe some smd might be malfunctioning. In which case, I will have to buy a completely new driver for it. So my question is if I want to repurpose the leds into a portable light unit with a 12V sealed lead acid battery, what kind of simple dc voltage regulation circuit should I built? 

     

     

    From the picture, I think the led is connected in a series. with forward voltage of 2-3V, connected in series of 4, coming up to 8-12V. Could I just connect the leds to the battery and be done?

     

    Thanks and best regards,

    YianIMG_0739.JPGIMG_0740.JPG

  • 14. Re: Do you have a question on LED/LCD lighting technology? Ask our Expert, Kevin Chen
    devendra30

    sir,
    i am doing my project on visible light communication.
    so will use LED array to transmitt data making it on- off(switching)
    how can i switch all the LED simultaniously???

    as i have only 1 output from the circuit.is there any IC available which can do this???
    i mean 1 input signal can make array on and off at higher rate???

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