12V LED Dimmer

Hi Guys,

I need some help to built a LED dimmer and control to my LEDs that i have in my night closet.

I don't have much information about them, but on label attached to the cable it says:

12V DC Max 5.8W.

They are just one color light LED.

Can someone help me with which components and circuit i can build an Dimmer with an Arduino?

Thanks in advance.

Regards,
Leandro

That's probably a constant current led power supply so the only way I think you can
"dim" it is to use a variable dc voltage regulator. You can't PWM a constant current
led supply. (it would just flicker)
Either you vary the dc input voltage or you replace the supply with completely different
circuit.

Can someone help me with which components and circuit i can build an Dimmer with an Arduino?

You will have to decide if which approach you want to take.
You can rule out any approach that involves PWM control of the 12V input to the constant current
led supply you have currently. That is not an option. You can buy a benchtop variable power supply
or borrow one from someone to experiment with lower input voltages for "dimming" the leds.
If that doesn't work for you I suppose you could return the supply and simply say you don't need it.

The question is , it this the only instance in your life where you will need to prototype an electronic
circuit. I hate to say it, but Electronics is not well suited for a "one night stand". Either you make a
commitment , or suffer the consequences of being a "weekend warrier". That's fine if you commit to
learning a little every weekend, but if you think you can just jump in , build one circuit and then give it up, I have news flash for you: Once you realize you can do it, you will come back for more and sooner or later you are going to wish you had a Benchtop variable dc power supply for prototyping. I started
out by building my own (38 years ago) . I built my first bipolar supply with foldback current limiting into a wooden cigar box. (probably not the best choice for a chassis by the way). It had fixed +5V,
+12V and variable +/-0 to 18V dc , using
LM723s

12V PWM CONTROLLED LM-317 VOLTAGE REGULATOR

LM-317 DATASHEET

The datasheet indicates the LM-317 can supply 12V dc out @ 1.5A (18W) (this would require a TO-220 HEATSINK)

Hi Raschemmel,

Thanks for the message.

To try give a little bit more information about the LED.

To turn on and off, there is a button, and there is 1sec fade effect when turning on or off. I assume there is some kind of circuit inside the button.

And the adapter provided says "is to use with LED only" and outputs 12V DC @ 1.25Amp, 15W

regards,
Leandro

Oh, I can think of a way to dim them, but it's really inefficient. Just dump the current through a parallel load controlled by a PWM mosfet. Enough about that though.

Did these led's come with their own power supply, or are you providing it?

They come with their own power supply.

You still have given us next to nothing to work with.
How about some photos of the equipment ?
It doesn't matter what it says really if they are leds then they behave as leds.
The only useful information is:

12V DC @ 1.25Amp, 15W

I need some help to built a LED dimmer and control to my LEDs that i have in my night closet.

I don't have much information about them, but on label attached to the cable it says:

As already stated, if they are leds, it is a constant current power supply and you can't PWM it.

As already stated, the only way to "dim" a constant current supply is to reduce the input voltage.
There is always the possibility that the result of doing this will be the leds dim up to a point and then the supply simply shuts down. If I had it, I would just hook it up to my variable bench supply and I would know in 60 seconds if it would work. How long have you spent on this post ?
Do you see my point. Either get on the bus or get off.
If you want to build your own dimmer then stop talking about the power supply that came with them because you can't use it for that (unless reducing the input voltage works, but we won't know that until you try it)

sorry I'm just trying to give much information as i can... I didnt got any manual or tech specs with furniture...

please check the images below:




Here's the manufacturer :
Why do't you ask them ?
In the photo it says clearly that it is a Model #1742

I'm thinking the button has the current limiting circuit. Maybe it can be hacked, maybe not. What is the ultimate goal? Just make it not so bright? Allow for on demand dimming?

The idea is to control the brightness of the LED, turn on and off and later add PIR sensor to fade on the LEDS on i get in the room.

Can i use the same adapter to power arduino and LED all together?

How do I know which value from 0 - 255 in arduino port will give max and min voltage to the LEDs?

I don't think you are understanding how that power supply works. The input to the led's is constant current, in which the voltage will increase/decrease in order to maintain the preset current limit.

I'm thinking that is a generic power supply and the current limiting circuit is in the push button housing, but I could be wrong. It's not in front of me. If it IS in the button housing, there has to be a microchip that regulates the current, and depending upon which one it is could be altered to achieve your goals.

If you can open the switch box and see what's in there, it will determine if it can be altered. You could also just forego all that and get a power supply that meets your criteria right off the bat, so you can just dive into the coding.