Starry sky is a sight that leaves no one indifferent.
With a little patience and the will, you can make the LED starry sky that will make your space extraordinary.
This is the plan for the simplest and cheapest LED starry sky that looks attractive and professionally done. For copies of the consumption of up to 500-600mA charger you can use the old mobile phone.
500mA is enough for 20 LEDs with I = 25mA
For larger quantities of LED and greater power consumption , use the AC adapter that can give higher power
All this you can see on LED Brilliancy with a few more tips about preparing the plate...

Step 1: Planning and Drilling

Determine the desired position and shape of the starry sky
That may be part of the ceiling (or the entire ceiling) in the room.
Sketch the surface of the Starry Sky in the appropriate
scale, and sketch LEDs.
It is important that you are satisfied with the arrangement and number of LED
Choose the type of material for the starry sky. it could be gypsum wallboard, plywood, acrylic and the like.
Surface cut into the desired dimensions, process the roughness and colored with the color desired. If the material is thicker than 5mm (this applies for all materials except acrylic ), LED-s are mounted on the outside (visible) side panels.
Drill holes for the mounting of LED-s according to the scheme you have outlined.
Drill hole 4.5 mm and carefully edging. Drill on the side where you predict that LED-s are.

Step 2: Preparing and Monting LEDs

Get a 5mm LEDs (this is the diameter LEDs) the best with  cutoff (flat) head and a bigger angle light scattering. Flat 5mm LED-s nicer acting on the plate, and if you have a wide angle scattering of light,  illuminates the plate which gives a nice visual effect. Important data are also power consumption and supply voltage. LED supply voltage is different for different groups of color LEDs. Some standard values are 2 to 2.5 V for red and amber LEDs and  2.5 to 3V for white, blue and green. Consumption of standard 5mm LEDs is 20-25mA. If you acquired the LEDs and you do not have accurate data for them, you can use these to calculate the current limiting resistor with a power adapter as will be described.
For each LED solder the cable the best red and black and red of course, to the anode and the black cable to catode. Length of cable set depending on the spacing and number of LEDs. You can connect them in groups of a few pieces and then connected to each other. View a photo diode connected and you all will be clear:
If you do not have an instrument to check, you can use 1.5V battery on whose statements you attach the red cable to the "+" and black cable to the "-". Connect the LED lights up when, remember that the legs is "+" with a battery and solder it to the red cable and the other black. Another way to identify the anode and cathode is that each LED in its cylindrical body has a small ring that is notched on one side. Legs with notched side is the cathode and on it goes "-" ie. black wire. Also, the longer leg is the anode . The legs should be cut before soldering the length of about 5mm. The cable should be of such thickness that it can freely pass through the hole on the plate. Solders should be as uniform without the excess tin.
With insulating tape Isolate each other legs. Use always the same length of tape.
Now thread the cable through the hole to lie on the surface of the LED boards. should to pass without getting stuck. then take a paper tape (the one used by painters to protect). Experiment to determine how the winding should be stuck into the hole LED. You can screw surface and create a spiral that would be better to get stuck in the hole. Do this carefully. When you develop the procedure, you will quickly prepare other LED with the installation.
You can also use glue or silicone to fix the LEDs into the holes.

Step 3: Selection and Calculation Power

Now the most interesting part of this project! How do you make the LEDs operate reliably without burning out.
You need a proper power supply and output voltage.
At the beginning of the text is said that you should know that the rated current and voltage of your LEDs and of course how many LEDs on starry sky.
For example, your starry sky has 20 LEDs, with the following characteristics:
U = 2.5 V (nominal voltage LED)
I = 25mA (nominal current)
First determine how strong the power source you need:
20 LEDs x 0.025 (mA turn in A) = 0.5A = 500mA
Almost every phone charger fulfills this requirement. If you have an old, look at his output characteristics. Usually U = 5V, I = 650mA or 750mA. Remember, the stream that writes to the adapter should be slightly greater than you need. This means you will not overload the power supply.
The next step is to determine the resistor that will reduce the adapter with 5V to 2.5 V as required for the LED.
The calculation is as follows:
U (resistor) = U (adapter) - U (LED) = 5V - 2.5V = 2.5V
R = U (resistor) / I (20pieces LEDs) = 2.5V / 0.5A = 5ohm
And in the end it is necessary to determine the power of resistor:
P (resistor) = U (resistor) x I (20pieces LEDs) = 2.5V x 0.5A = 1.25W
When you purchased resistor, please take a greater power than calculated, because it will be less heat and reduce the risk of burning out. For example, if you calculate the P = 1.25W, you can take 2W .
As for the resistor values in ohms, you will not go wrong if you take 10-15% greater value than calculated, because this reduces the current through the LEDs and even prolong their life. Starry sky will shine a little less, but you will certainly use it as a decorative lighting system
Remember that LEDs connected in parallel as a schematic and have to be all related to the rectifier through the resistor and then connect the adapter voltage. If for example, connect a single LED it can burn out, because the resistor will not drop enough voltage.

Step 4: Installation of the Ceiling

All that remains is to mount the starry sky on the ceiling and enjoy.
As for installation, it is important to bring the high voltage to rectifier. Be sure to disconnect the circuit when you merged the high voltage rectifier. If you are not an electrician, let that part of the a professional. Remember that high voltage is dangerous to life!
Mounting must be safe, use proven parts.
If you want to use much more of LEDs to create your own starry sky, you can use few boards that will connect with each other, but the supply must be stronger with more resistors for multiple groups of LEDs.

About This Instructable




Bio: man who don't know too much, but know enough
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