Results 1 to 6 of 6

Thread: Star strobe Question

  1. #1
    Senior Elf member johnpdo's Avatar
    Join Date
    Oct 2013
    Location
    close to Buckner, MO....only, out in the country
    Posts
    152

    Star strobe Question

    I bought a set of 32 (8 each red, blue, green, white) start LED's in a small group buy 2-3 years ago. Maybe more. Just getting around to them.

    I think they were 1 watt leds. I am wiring them up finally, and when I put 5v power to them, they are super bright.

    Problem is, 1 red one burned out pretty quick (2-4 seconds). I quit testing them, as I am thinking I may need to put a resistor on them.

    Did I just get 1 bad led, or am I going to burn them all out quickly?

    Planning on making them into little plastic containers, for sparkly strobes. 100 or so msec on vixen, on my megatree.

    Do only red ones need resistors, or all of them, and what size resistor should I use?

    Thanks!
    Attached Thumbnails Attached Thumbnails suntekstore1486548191_image.jpg  

  2. #2
    Frosty member
    Join Date
    Nov 2014
    Location
    Sauk City, WI
    Posts
    943
    Sorry to hear about the magic smoke... you are on the right path. I couldn't find the group buy you referred to or the led you show but generally LEDs need resistors. You can find the calculator online. You do need to know the forward voltage of the LED.

  3. #3
    Santa member dirknerkle's Avatar
    Join Date
    Nov 2011
    Location
    Plymouth, MN USA
    Posts
    9,956
    We also have a Wiki page that outlines the normal forward voltages and recommended maximum currents for lots of LEDs:

    https://www.diychristmas.org/wiki/in...ent_Statistics
    Even though the DIGWDF Store has closed, it's still awesome! Thanks to all who have supported us through nearly 7 years of excitement!
    Parts of the store will remain open for downloading documentation, firmware and Gerber/DipTrace files: http://digwdf.com/store

  4. #4
    Frosty member TomL8345's Avatar
    Join Date
    Dec 2013
    Location
    Chambersburg, PA
    Posts
    898
    Quote Originally Posted by johnpdo View Post
    I bought a set of 32 (8 each red, blue, green, white) start LED's in a small group buy 2-3 years ago. Maybe more. Just getting around to them.

    I think they were 1 watt leds. I am wiring them up finally, and when I put 5v power to them, they are super bright.

    Problem is, 1 red one burned out pretty quick (2-4 seconds). I quit testing them, as I am thinking I may need to put a resistor on them.

    Did I just get 1 bad led, or am I going to burn them all out quickly?

    Planning on making them into little plastic containers, for sparkly strobes. 100 or so msec on vixen, on my megatree.

    Do only red ones need resistors, or all of them, and what size resistor should I use?

    Thanks!
    I believe you took part in a GB for Dirk's Cheap Strobes. The idea is to wire 5v directly to the LED, but only use extremely short on intervals to keep the light cool and working. I have been using the White version of these strobes for years, the only problem I have had is when some channels got stuck on and burned out the LED and melted the plastic case some.
    2012 - 1st year 64 Channels - 7500 LED lights - 5 sequences
    2013 - 128 Channels - 10,000 LED lights - 7 sequences (2 New)
    2014 - 201 Channels - upgrading 8 Arches to dumb RGB - 8+ sequences (1+ New)
    2015 - 240 Channels + 8 Universes - sequences TBD
    2016 - No Display
    2017 - Back in the Game - 240 Renard Channels + 12 Universes
    2018 - 256 Renard and 9 Falcon Outputs of Pixels - 16 sequences shown over 2 nights

  5. #5
    Santa member dirknerkle's Avatar
    Join Date
    Nov 2011
    Location
    Plymouth, MN USA
    Posts
    9,956
    John,
    Use the Wiki page to find out the specs on the led. For example, for a 1W red led, the forward voltage is 2.2v and the current is 350ma.

    Go to this link: http://led.linear1.org/1led.wiz

    Plug the values in along with the voltage source you intend to use. For a 5vdc power source, 2.2v forward current and 350ma, it will calculate an 8.2ohm, 2watt resistor. I've found that with LEDs you'll have better longevity if you don't run them at their maximum, and if if you decide to run them at 75%, that would be running it at 262ma instead of 350. That will calculate out to a 12ohm, 2w resistor at 5vdc.

    Play with the tool, and use it to come up with other values for the other colors.

    In my case, I powered them from an LSD board which maxxes-out at 300-350ma of current from the 2N2222a transistors. So I reasoned that I could run those 1W leds direct from the controller without any resistors at all for short periods of time and not damage them. That proved to be the case and they worked great as small strobes. Sometimes I'd convert a strobe into a light source which might stay lit for 3 or 4 minutes at a time (the duration of a whole sequence) and for those, I'd add a 10ohm 1W resistor and they worked great, too. (I used 1W because I didn't have any 2W.... at DIGWDF, close was good enough....LOL)
    Even though the DIGWDF Store has closed, it's still awesome! Thanks to all who have supported us through nearly 7 years of excitement!
    Parts of the store will remain open for downloading documentation, firmware and Gerber/DipTrace files: http://digwdf.com/store

  6. #6
    Senior Elf member johnpdo's Avatar
    Join Date
    Oct 2013
    Location
    close to Buckner, MO....only, out in the country
    Posts
    152
    Thanks everyone! I will play with them for sure. I am going to run them off an LSD board also, so that should help, and since I am going to just fire them off as a twinkle effect, they won't be getting long bursts, either. I think they will be safe.
    I made my 1st one burn out by just putting it to 5v on the bench power of 5v from an old computer power supply. I should have known better, but it was a bright shiny moment, for a little while :-)
    Trying to get one new element either fixed or made each month of this year, and February is quickly getting done.
    Stay warm, and tinker away.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •