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How to reduce the brightness of the led strip without dimmer?

opsops 20964 14
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Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
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  • #1 15518403
    opsops
    Level 9  
    My led strip shines too brightly, I would like to dim it a bit using e.g. a resistor.
    ~ 9 watt per 12 volts tape.
    Which resistor to choose?
    Or maybe you have a better idea?
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  • #2 15519314
    wzielonymgaju18
    Level 18  
    You can power the tape with less voltage. For example, via a 9v power supply.
    You can also use a driver for RGB tapes, it is attached between the tape and the power supply. It costs about PLN 10 and in addition to dimming with the remote control, it has options for remote switching on and off, lighting effects, etc. and remembers the last set value.
  • #3 15519342
    hobbyelektronik
    Level 27  
    Give 1 or 2 1N4001 diodes in series, it should work, on each you have a voltage drop of about 0.7V.
  • #4 15519551
    retrofood
    VIP Meritorious for electroda.pl  
    opsops wrote:
    My led strip is shining too bright, I would like to dim it a bit


    You can stick on it, for example, dark, opaque tape.
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  • #5 15519696
    opsops
    Level 9  
    The option with the tape is not available, I will try with the LEDs.
  • #6 15520250
    bartek_p
    Level 31  
    Get yourself a DC motor speed controller. You will have full adjustment without any problems.
  • #7 15522579
    deus.ex.machina
    Level 32  
    bartek_p wrote:
    Get yourself a DC motor speed controller. You will have full adjustment without any problems.


    Actually, the only correct answer in the thread ... the tension lowering suggestions could be considered harmful advice ...
  • #8 15522635
    Xantix
    Level 41  
    deus.ex.machina wrote:
    Actually, the only correct answer in the thread ... the tension lowering suggestions could be considered harmful advice ...

    Why harmful? And how is the brightness of the LEDs reduced? By reducing their current. And since the tape diodes have built-in limiting resistors, the current change occurs by changing the supply voltage. BTW. This "DC motor speed controller" works just like that - it lowers the output voltage.
    You can also use a power supply with adjustable output voltage - it will work the same.
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  • #10 15525835
    hobbyelektronik
    Level 27  
    The question was: How to reduce the brightness of the led strip without dimmer?
    the LM317 chip is in a way a variation of it, as well as other varieties of PWM controllers for the drill.
  • #11 15525864
    gosztekseba
    Level 31  
    Well, in my opinion, the idea of rectifying diodes in series and a dark tape is probably the exact answer to the question "How to reduce the brightness of the led strip? without dimming ? "

    If, however, a colleague of the author would like to build such a dimmer, I urge you to do so, of course, I recommend the PWM method, even NE555 + MOSFET - lower losses compared to linear stabilizers. Regards
  • #12 15527815
    deus.ex.machina
    Level 32  
    Xantix wrote:

    Why harmful? And how is the brightness of the LEDs reduced? By reducing their current. And since the tape diodes have built-in limiting resistors, the current change occurs by changing the supply voltage. BTW. This "DC motor speed controller" works just like that - it lowers the output voltage.
    You can also use a power supply with adjustable output voltage - it will work the same.


    It is simply impossible to lower the voltage below the forward voltage, which for a typical white (blue) LED is 3.4 - 3.6V - usually in the strip you have 3 LEDs connected in series, the voltage change is possible to a small extent and I do not see any chances that the 9V power supply will enable the correct operation such a series.

    hobbyelektronik wrote:
    The question was: How to reduce the brightness of the led strip without dimmer?


    Each method described above will be a dimmer, so it does not meet the conditions of the question if you take it literally - you could maliciously say that the author should change the resistors in the tape then the above condition will be met - no additional "dimmer"
  • #14 16075434
    paputek11
    Level 11  
    and I have such a problem, I bought a 12v led strip and connected to the car installation a strip maybe 20 cm, it shines ok only how to make it possible to dim, maybe some adjustment? resistors hmm too much fun with matching it seems to me, unless you tell me which to use, the LED will be on all the time while driving the car
  • #15 16075565
    markovip
    Level 34  
    @opsops Please show the photo of the power supply. Some are regulated ...
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Topic summary

To reduce the brightness of a 12V LED strip without using a dimmer, several methods were suggested. One approach is to power the strip with a lower voltage, such as using a 9V power supply. Alternatively, adding 1 or 2 1N4001 diodes in series can achieve a voltage drop of approximately 1.4V, effectively dimming the LEDs. Another suggestion is to use a DC motor speed controller, which allows for adjustable brightness by lowering the output voltage. Some participants mentioned using opaque tape to block light, although this was deemed less effective. The discussion also highlighted that methods like using an LM317 driver or PWM controllers could serve as dimmers, but these technically do not meet the original request for a solution without a dimmer. Concerns were raised about the potential harm of reducing voltage below the forward voltage of the LEDs, which typically ranges from 3.4V to 3.6V for white or blue LEDs.
Summary generated by the language model.
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