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Thread: Begginer needs your advice :D

  1. #1

    Default Begginer needs your advice :D

    Good day!

    I'm planning to build video light for my umbilical to put on my helmets.

    Ordered 12v LED star (China).

    Do I need to use any driver if I would like to use this LED only in one mode(max)? Can I connect it directly to my 12v power supply?

    Best regards
    Arthur

  2. #2
    Flashaholic* DIWdiver's Avatar
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    Default Re: Begginer needs your advice :D

    Hi, and welcome to the forum!

    You can connect it directly to your 12V supply if it was designed for that. Otherwise it will not work as desired, with instant catastrophic failure quite a significant possibility. Oh, and few if any stars are designed for that.

    Unless your 12V supply has adjustable or known fixed current limit and you keep the current at or below the max specified for the star. Then it will not be operating as a voltage source, but as a current source, AKA an LED driver.

    Also keep in mind that no star should be operated at rated current without additional heatsinking. You can overheat it and burn it out in a matter of seconds, maybe tens of seconds depending on the star.

    Specific information about the star and the emitter(s) on it would be required to make any recommendation.

  3. #3

    Default Re: Begginer needs your advice :D

    DIWdiver,

    Many thanks for your reply!

    I'm planning to use a different 12v power source, like a car battery, boat battery, and Pb power bank.

    At this moment the light is connected parallel with CCTV camera power source. (unfortunately, umbilical don't have available cores to connect light separately and make it dimmable)

    At the moment light use 12v 10w emitter (theoretically 900lm) unfortunately its too low.

    Now I order star with following specs:

    Brand:Cree
    Emitter Color : Cool White
    Color Temperature :6300-6500k
    Base : 20mm Copper Board
    Size (mm x mm) :5.0 x 5.0
    Maximum drive current (A) :1.5 (12-V)
    Maximum power (W):19
    Light output :Up to 2546 lm @ 19 W
    Typical forward voltage (V) - white :5.75 @ 1400 mA (12-V)
    Viewing angle (degrees) :120
    Binning :85°C, ANSI White, 2-, 3- & 5-Step EasyWhite?
    Thermal resistance (°C/W) :1.2
    Reflow-solderable :Yes – JEDEC J-STD-020C-compatible
    RoHS and REACH-compliant :Yes
    UL-recognized component :Yes – Level 4 Enclosure Consideration


    I have enough space to insert an aluminum or copper radiator.

    The voltage on the light end is 12.3-12.5V depends on a battery charge. Unfortunately, I don't know how much Amps.

    Maybe someone from Europe can recommend where I can get AGRO glands? I order 2 pcs from eBay it costs 17 EUR/pcs is it normal price?

    Chinese glands are shi** and need to be sealed by epoxy or other glue.


    Many thanks and sorry for my bad English








    Quote Originally Posted by DIWdiver View Post
    Hi, and welcome to the forum!

    You can connect it directly to your 12V supply if it was designed for that. Otherwise it will not work as desired, with instant catastrophic failure quite a significant possibility. Oh, and few if any stars are designed for that.

    Unless your 12V supply has adjustable or known fixed current limit and you keep the current at or below the max specified for the star. Then it will not be operating as a voltage source, but as a current source, AKA an LED driver.

    Also keep in mind that no star should be operated at rated current without additional heatsinking. You can overheat it and burn it out in a matter of seconds, maybe tens of seconds depending on the star.

    Specific information about the star and the emitter(s) on it would be required to make any recommendation.
    Last edited by a.seiko; 08-12-2018 at 11:14 PM.

  4. #4
    Flashaholic* DIWdiver's Avatar
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    Default Re: Begginer needs your advice :D

    Your English is plenty good. I understood '**" perfectly!

    Running an LED that's nominally 12V from a 12.3V source is possible, but it's quite possible you won't be able to drive it to full rated current unless you have a buck-boost type driver. Something like this might do a nice job: https://www.ebay.com/itm/5-30V-to-0-...LH_TitleDesc=0. Now THEY should apologize for their English! I don't know of anyone who makes small ones.

    You should determine whether you have the '6V' version or the '12V' version. You said you have the 12V, but then said the Vf is 5.75V. That doesn't match.

    If you are lucky and Vf really is a bit less than 12V, then a low-dropout linear or buck type regulator would work quite well. Those are more available in small sizes. Unfortunately there's no way to know what your actual Vf is until you get the LED and run it. The datasheet will specify "typical" and "maximum" values. If you get one that's up near the max, this wouldn't work as well.

    If you actually have the 6V version, then you really would want a buck type driver. These are plentiful.

  5. #5

    Default Re: Begginer needs your advice :D

    I ordered 12v version, looks like description/specs for both 6v and 12v are same on eBay Chinese


    Already have many of these voltage/current adjustable board from my other projects. Do you recommend to set up 12v and max allowed current? Or run it directly from my power source and if a light is enough don't use this module?

    I will build light like SSVTEC therefor I have enough space to put module with the big radiator to avoid overheat https://www.dropbox.com/s/cmgi7huzmx34tir/ight.jpg?dl=0


    Yesterday find interesting Chinese light JAUNT Vision 170 Degree Wide Beam 8000 Lumens LED. Looks like it really has a 170-degree angle. Interesting how the Chinese do that. Because it uses led with 115-degree angle?




    Many thanks for your patience.

    Regards
    Arthur
    Last edited by a.seiko; 08-14-2018 at 01:55 AM.

  6. #6
    Flashaholic* DIWdiver's Avatar
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    Default Re: Begginer needs your advice :D

    I would definitely NOT recommend connecting the LED directly to any power source able to deliver more current than you want in the LED.

    The adjustable voltage/current boards are great, but keep in mind that there is always some minimum voltage loss from input to output. In some it can be as little as 0.1V, or it can be as high as 1V or even 2V. This is called the overhead voltage. Once the difference between the supply and the LED is less than the overhead voltage, the output current will start to drop, and the LED will start to dim.

    For example, say your LED draws 1.5A at 12V, and your regulator's overhead voltage is 0.5V. When your battery starts out at 12.6V, everything is great. Battery drops to 12.5V, everything is still fine. Battery drops to 12.4V and things start to change. The output voltage can only be driven to 11.9V (12.4V minus the 0.5V overhead). The LED will still work at 11.9V, but it will no longer draw 1.5A and won't be as bright. Battery drops to 12.3V, output goes to 11.8V, LED gets dimmer.

    But say you had 1.0V overhead. This would never be able to drive the LED to 12V, and thus not to 1.5A. However if you switched to a 6V, 3A LED, the regulator would happily drive it at full power until the battery dropped to 7V. A good switching regulator could do this with quite good efficiency.

  7. #7

    Default Re: Begginer needs your advice :D

    Good day!


    Today I "finished" my light for commercial diving umbilicals.

    I use an Aluminium radiator due to fact that I have only aluminum and bronze in my workshop.

    The light head was made from "Plastic" I don't know that is it, but it looks very strong.

    The lens is 6mm glass, it allow to use this light during welding I have it at my workshop, therefore light head was made to fit the glass.

    Find only one available AGRO gland on eBay.

    Use this LED star without a driver, connect it directly to a 12.5v battery pack.

    Test this light in a 5L bowl for 2hour. Works very good. Glass lens helps to reduce heat very good.

    Light angle is about 160-165 degree.

    Don't judge me, I'm a beginner


    https://www.dropbox.com/sh/refxuoovi...zemS0FZLa?dl=0





  8. #8
    Flashaholic* lucca brassi's Avatar
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  9. #9

    Default Re: Begginer needs your advice :D

    Many thanks! I will check

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