Dimmable LED Driver with Non-dimmable LED's

Discussion in 'The Projects Forum' started by Humanist, May 13, 2016.

  1. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    Can I connect non-dimmable LED's to a dimmable LED driver? I do not intend on using a dimmer. Just a switch.
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,773
    1,103
    We would need to know the detailed specs of the LEDs and the driver.
    Welcome to AAC!
     
    Humanist likes this.
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,986
    3,730
    I would say, it is possible. However, I don't think it is safe. What prevents anyone from adjusting the dimmer once you install the non-dimmable LED?
     
    Humanist likes this.
  4. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    Thanks for the welcome. I'm trying to make an aquarium light with a simple on\off switch. No dimmer. I've got a test strip of 6 LED's which I plan to double. Please see diagram for driver and LED specs.

    6 LED circuit diagram_Driver.jpg
     
  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,986
    3,730
    You should be fine.
     
    Humanist likes this.
  6. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    I'm a total noob to anything electrical and really bad at math to boot but it also seemed to me that it would work. However...
    I've tried it twice and had two, albeit slightly different, failures.

    The first time I connected the LED's they flashed briefly then died. I could not get them to work at all after that. I then tested the LED's individually and they were fine. I then connected a boost converter to the same string and all the LED's worked.

    I then tried adding a seventh LED to increase the load on the driver. I connected the driver and only 2 of the LED's (first two in the string) lit up for around 10 seconds before dying.

    I must also add that I am new to soldering :)
     
  7. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    I'm thinking either you don't have 1 watt LEDs or you don't have a LED driver that works.
    This part is difficult to interpret:
    The LEDs could not have died and then worked later. I must assume the LEDs did NOT die, they just stopped making light. Now that we have stopped believing the LEDs are dead, it's time to turn attention towards the Driver. What do you have for a meter? Can you measure volts and milliamps?
     
    Humanist likes this.
  8. BobTPH

    Active Member

    Jun 5, 2013
    782
    114
    LEDs are not non-dimmable. LED light bulbs might be, but not raw LEDs.

    Bob
     
    Sinus23, Humanist and #12 like this.
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,773
    1,103
    For LED longevity it is not a good idea to run them at their full rated current (especially as manufacturers's figures can be a tad optimistic). About 75%-80% of that value (say 250mA) would be better. Turn the dimmer control down to about half way and get the LEDs working, then crank up the dimmer control a bit.
     
    Humanist likes this.
  10. #12

    Expert

    Nov 30, 2010
    16,252
    6,751
    This idea is a bit difficult too, considering the Thread Starter said,
    and
     
    Humanist likes this.
  11. hp1729

    Well-Known Member

    Nov 23, 2015
    1,939
    218
    Specific part numbers or data sheets would be helpful.
    What you described might just be the LEDs getting too hot. As suggested, try driving them at a lower current.
     
    Humanist likes this.
  12. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    (DIY Aquarium LED expert here..built many fixtures)

    Those "ARE" dimmable LEDs..

    Your diagram is wrong.. The LEDs are shown backwards.. The + output from the driver should go to the + of the first LED

    What are you attaching the LEDs to? do you have a circuit board?
    What are you doing for heatsinking? You can quickly overheat and destroy the LEDs if not heatsinked properly..
     
    Humanist and #12 like this.
  13. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,986
    3,730
    Because the LEDs still work after connecting them to this power supply, that the power supply is shutting down rather than LEDs getting damaged.

    The supply is 300mA constant current and can supply that constant current (stay in compliance) over the stated voltage range. Note that higher voltage loads will be easier for the power supply to maintain compliance and it has to dump more energy as heat when supplying a load closer to the bottom of the acceptable output voltage range. Again I am guessing without a datasheet but your power supply cannot really handle loads with such a low voltage when really designed for 50+ volts.

    I would either add more LEDs in series (notice that it stayed on a bit longer when you did do that - be for it overheated), or, you can try to force the voltage drop outside of the power supply with a dropping resistor. Let a resistor drop 30 volts at the rated 300 mA. That can simply be a 100 ohm 10 watt sand-bar (100 ohm x 0.3A = 30V).

    Good luck
     
    Humanist likes this.
  14. hp1729

    Well-Known Member

    Nov 23, 2015
    1,939
    218
    Will the constant current circuit CAUSE 300 mA to flow or just limit it to 300 mA. Could sticking in a resistor bring the current down to 250 mA?
     
  15. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    Apologies if my terminology is a bit vague or just plain incorrect. With all the help and suggestions I'm getting I'm learning fast though. I have a no name brand digital multimeter and I have managed to measure both volts and milliamps through the circuit. but only when I used the boost converter which kept the LED's on long enough for me to measure. Below is a screen shot of the driver. Screen shot 2016-05-14 at 9.26.25 AM.png
     
  16. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    I did have a fleeting moment of thought and tried a 1ohm resistor in series but still no cigar.
     
  17. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
     
  18. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    Thanks! I'll give it a go too. I had a similar unqualified thought but did not add enough resistance. Will try more.
     
  19. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
     
  20. Humanist

    Thread Starter New Member

    May 12, 2016
    11
    0
    Apologies for the mistake in the diagram. I will recheck the wiring. I have not made a permanent attachment to a heatsink just for short bursts for testing purposes. The LED's are kept in place with a small piece of pressure sensitive adhesive. and electrical taped the connecting wires to a piece of wood.

    I assumed the LED's were not dimmalbe just because of the specs on Aliexpress which says 'dimmable: no'
    And after my failures I assumed that this was problem.
     
Loading...