Eye bulb enlightner LED

Hi Giuseppe,

Check out this link: I Want to Do Electronics!  Where do I start?

Also there are circuits at talkingelectronics, if you hit ctrl-F and search for 'dimmer' you'll find an example. Its not as simple as just a potentiometer and an LED, it implements 'PWM' (which can be googled).

But, you could (should) also experiment with LEDs and a pack of resistors, a 9V battery and a potentiometer, to see how things behave, it might suit your needs. You'll need these parts anyway even if you later decide you want to improve the circuit. For the formula, the LED wikipedia page is not bad, it will send you to a link with an LED circuit, which has some calculations.

Thanks a lot shabaz!

I'll check tonight during my night shift XD I really need to learn because I always curious and thirsty of knowledge XP

Yes, if you have everything ready is better but you lose the funny

Giuseppe, you face two issues here, basically.  One is the non-linear characteristics of the LED.  The other is the Weber-Fechner law:

https://en.wikipedia.org/wiki/Weber%E2%80%93Fechner_law 

Hi Don Hersey, sorry can I ask you to be more specific and simple, because i don't understand the issue that you tell me... Sorry and thanks for your help

Maybe I didn't put enough information, I would like use a high potential LEDs and with a potentiometer I would like to reduce the intensity of the light, I don't need a realy bright light because can hurt the human eye.

The problem with that, Guiseppe, is that the delta impedance of your LED around threshold is low and temperature dependent.  So, a driver as you describe it would either not turn the LED on very well, or risk turning it on too much.  Typically, only signal LEDs are energized through a resistor, because it is easy to waste lotsa power through the ballast resistor.  So, the designers of high-power LED drivers with chopping schemes, much of the ballast R being replaced by L, which powers the LED during the no-supply-current interval.  You can order dimmable LED drivers that are chopping and current-mode output.  These will do what you want efficiently.

Weber-Fechner states that for the perception of a stimulus to a biological system to seem to double in power, it must actually be squared.  This is why volume pots on audio amps tend to be non-linear.

I search on line for a wile to see wich product could be the best for me... So you sudgest to use a dimmer for led powered by a 12 volt battery and easily connect the 2 high power LED with an wire extention?  Am I correct?

So, do you sudgest to use a dimmer powered by a 12V battery and join wit a extended wires the 2 LED?

So,  if, for example,  I use this dimmer powered by a 12v battery and on the output I connect 4 extensions wires and in the and  the 2 LED it will be fine right?  Or I need to protect the LED with resistences?

https://www.amazon.co.uk/gp/aw/d/B00K67Y47C/ref=mp_s_a_1_11?ie=UTF8&qid=1474399627&sr=8-11&pi=AC_SX236_SY340_FMwebp_QL65…

Hi Giuseppe,

I'm afraid I know as much about it as you do. This dimmer isn't an electronic component with a datasheet, it is an end product with little information on that page. Also we don't know what LEDs you want to dim. A light strip as shown on that page isn't just an LED or LED(s). It is a circuit of LEDs and resistors. It can be driven with no series resistor because the resistors are already in the circuit.

That linked product might work but I'm only guessing given the photo where they show it connected to a strip. It might not work. It is unlikely to damage a strip of LEDs+resistors designed for a 12V supply. It is cheap so maybe worth a try. No guarantees.