confused about led´s

[ayayeyey]

Been reading about LED but some things are very confusing, maybe someone here knows an answer to some of my questions.


Some people say led light cannot be dimmed, but i see led dimmers are available, is it so that only special led lights can be dimmed?

If i want to use a 12v rgb led strip, i would like to buy an 12v power supply, but it seems like i would also need a led driver in order to get a longer life span out of the led´s. Does the need for an led driver only apply for certain leds? Or is it always good to use an Led driver?

Can all kinds of rgb led´s be connected to an DMX controlled system, or does one have to special order rgb led´s especially made for DMX control?

Of course a limited amount of led light modules can be connected to a certain power supply, and if i want to add more, i would need to get an additional power supply, but is this also true for an rgb controller? Or can an rgb controller be connected to as many led modules as i want?


What does superflux means?

 

[HKJ]

Leds are very easy to dim, but when you buy them as a "light bulb", they include some driver electronic and that driver is usual not compatible with a dimmer.

Leds nearly always needs a driver (Some flashlight can get around that), sometimes the driver is included in the led assembly, other times you need to supply you own driver.

For use with a dmx system, you need a driver that understands dmx and only drivers designed for dmx use does that, i.e. only leds where dmx is specified can be used on a dmx system!

Any kind of controller or drive has a limit, you can usual find it in the specifications.

 

[ayayeyey]

Thank you very much for your answer!

Leds nearly always needs a driver (Some flashlight can get around that), sometimes the driver is included in the led assembly, other times you need to supply you own driver.

But for example, a lot of times i see shops selling led strips and led smd modules, and never have i seen in the product description text that i need a driver also, do these strips, smd modules, usually include drivers?

 

[HKJ]

But for example, a lot of times i see shops selling led strips and led smd modules, and never have i seen in the product description text that i need a driver also, do these strips, smd modules, usually include drivers?

A driver can be as simple as a resistor and I believe that is usual the case when a led module is rated for 12 volt. A white led need somewhere between 3 and 3.7 volt on its own, connecting 3 white led in series and adding a resistor will give you a 12 volt module.

 

[yellow]

there is probably no mention to "need" some kind of current limiting for the led (real driver, resistor, ...) because its the part of the user to care for that

analogy: when getting a halogen bulb, the user has to take care for the right number of battery cells, ...


"not being able to be dimmed":
I dont get that, who told You that?
ANY light source can be dimmed, the differenc is that led still give useable light with reduced power, while halogens f.e. do not offer that range of usefulness.
(PS: I would not take the advise of such "informants" as the single correct one)

 

[Light Sabre]

I think he's thinking of 120 VAC LED light bulbs. Most of them can't be dimmed using an AC light dimmer. Don't know which goes the bulb or the dimmer. With 120 VAC CFL bulbs it's the light dimmer that goes and can become a fire hazard. Some of the LED bulbs and CFL can be dimmed. Usually says on the package or the bulb which kind it is.

 

[2xTrinity]

I think he's thinking of 120 VAC LED light bulbs. Most of them can't be dimmed using an AC light dimmer. Don't know which goes the bulb or the dimmer. With 120 VAC CFL bulbs it's the light dimmer that goes and can become a fire hazard. Some of the LED bulbs and CFL can be dimmed. Usually says on the package or the bulb which kind it is.

This is really more the fault of the dimmers than the light bulbs. Those dimmers -- which basically chop off a portion of the AC sine wave, are only suited for use with incandescent lamps, or CFL/LED/other types of lamps with extremely complicated driver circuits specifically designed to work with triac dimmers.

 

[PhotonWrangler]

LEDs are more commonly dimmed using pulse width modulation. This provides a steady regulated current when they're on. A lot of LED tail lights use PWM to change from dim to bright when you hit the brake pedal. Here's a PWM LED driver schematic.

Professional DMX dimmer circuits intended for LEDs will also use PWM to achieve a full range of dimming without hurting the LEDs.

 

[ayayeyey]

A driver can be as simple as a resistor and I believe that is usual the case when a led module is rated for 12 volt.

Ah, ok, thanks, things are starting to get a little clearer now

A white led need somewhere between 3 and 3.7 volt on its own, connecting 3 white led in series and adding a resistor will give you a 12 volt module.

So if a 3 x 3,7 v leds would result in a 12v module, then i would assume the rest of the 0.9 v would somehow be created by the resistor.

 

[ayayeyey]

there is probably no mention to "need" some kind of current limiting for the led (real driver, resistor, ...) because its the part of the user to care for that

For the "average joe" who just recently, and with no background as an electrician, as myself, got interested in experimenting with led light, i do not think it is too obvious.

"not being able to be dimmed":
I dont get that, who told You that?

I read it somewhere, and as someone in this thread pointed out, i think it might have been about led light bulbs.

 

[ayayeyey]

This is really more the fault of the dimmers than the light bulbs. Those dimmers -- which basically chop off a portion of the AC sine wave, are only suited for use with incandescent lamps, or CFL/LED/other types of lamps with extremely complicated driver circuits specifically designed to work with triac dimmers.

hmm, interesting

 

[ayayeyey]

thnx for the other answers as well, very interesting.

 

[ayayeyey]

i usually read about regular 5mm led´s, 10mm led´s, but where are they measured? Is it the diameter viewed from above?

Or is it the whole actual led body, except the legs, that is 5mm?

 

[HKJ]

So if a 3 x 3,7 v leds would result in a 12v module, then i would assume the rest of the 0.9 v would somehow be created by the resistor.

That would be a good guess or it could be a constant current driver chip (Like 7135). Both solution will work, the chip is better if the 12 volt does swing a little bit.

 

[bshanahan14rulz]

5mm is the diameter of the cylindrical body.

what does your name mean? .

:welcome:

 

[ayayeyey]

That would be a good guess or it could be a constant current driver chip (Like 7135). Both solution will work, the chip is better if the 12 volt does swing a little bit.

Ok, i often see the company who sells led modules/strips also sells different kinds of power suppliers, is it common that those provide voltage swings?

Is it almost like a rule that, the cheaper the DC power supplier is, the bigger risk it will provide voltage swings?

 

[ayayeyey]

5mm is the diameter of the cylindrical body.

what does your name mean? .

:welcome:

My name does not mean anything. Btw, what happened with Brandon Shanahan, is he still in Detroit?

Thank you for the answer and the welcome! :wave: