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What voltage are these clear color LEDs?

Discussion in 'General Electronics Chat' started by gary350, Aug 5, 2017.

  1. gary350

    gary350 Well-Known Member

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    These lights are not very bright. It is 50 feet across my work shop I set the light on 1 side of the room and turned the lights on in the shop. I can see the sign but its not very bright all i see is 8 bulbs not the arrow sign. If I had the sign in the front yard people driving by will probably never see it. If I take it camping people 100 ft way walking by in the dark will probably never notice the sign.

    1 light got dim then few minutes later it stopped working. About 10 minutes later another light got dim and stopped working. Maybe 5v is too much for them. I removed the glass that covers the LED ohm meter says there is no resistance from the screw base to the LED wires. 6 good light bulbs left.
     
    Last edited: Aug 8, 2017
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    That's probably why the sign was in the yard sale ;).
     
  3. gary350

    gary350 Well-Known Member

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    if I had replacement bulbs that put out brighter light it would be a good sign.
     
  4. dave

    Dave New Member

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  5. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You can buy cheap Chinese LEDs on ebay and they are extremely bright. BUT they are bright because their case focusses the light into a very narrow beam that cannot be seen unless the LED points directly at your eyes.
    Modern Western LEDs are not cheap but are worth it because they are very bright with a wide viewing angle.
     
  6. gary350

    gary350 Well-Known Member

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    Not sure I want LEDs in this sign again the ones I have look no different than 8 LEDs attached to a wooden dowel rod in the dark from 50 ft away. I see tangled wads of Christmas tree lights at yard sales all the time 25ยข. I can cut the wires, rewire them for a power supply that I have once I test them, I think they are about 2v per light. New screw in bulbs would be easier if I could find them at a reasonable price some I looked at are 2 pack for $5. I am not going to buy $20 worth of bulbs for this sign. This sign will work better with about 30 bulbs.

    Christmas tree lights are such a poor design for the buyer if 1 light burns out it sometimes takes a whole hour to figure out which one is bad. Several years ago I cut up several strings of Christmas lights then rewired them all in parallel. I connected them to a low voltage transformer they work good.

    Nice thing about being retired I have time to play with silly stuff like this sign. I am about ready to throw it in the trash i already had $2 worth of fun with it. LOL.
     
  7. audioguru

    audioguru Well-Known Member Most Helpful Member

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    One LED part number has a datasheet that shows its range of forward voltage. A red one (MV8191) could be 1.5V to 2.4V or any voltage in between. If you randomly connect some LEDs in parallel then the one with the lowest voltage will hog all the current and quickly burn out. The higher voltage LEDs will not light until the lower voltage ones burn out.
    Chinese flashlight manufacturers pay somebody to test and group the voltage of their LEDs so that all the LEDs in a flashlight with them in parallel have a matched voltage.
     
  8. gary350

    gary350 Well-Known Member

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    I have a bunch of LEDs, all colors, no part numbers, no information. They probably all need a different value resistor to connect them to a battery. Probably very low light LEDs.

    I know if you connect a 100w 120v light bulb in series with a 60w 120v light bulb then connect them to 240v the 60 light will burn out. Same thing with heating elements.

    LEDs are not very forgiving.

    I have several Harbor Freight free flashlights those things are junk they last about 1 week and stop working. They have 9 LEDs on a circuit board that light up on 3 AAA batteries. Circuit board shows all 9 LEDs are in parallel with no resistors.
     

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