Intro: Custom LED Sign
Ever wanted to make an led sign for one of your projects? Now you can! In this instructable I will show you how to make your very own led sign. I will cover everything from designing your sign on a computer to calculating led values.This was my first soldering project and it turned out great! Make sure to read this whole instructable before you start.
Step 1: Materials
What you will need:
perf board without pads
2 colors of sharpie
DC power supply
dremel or saw
*I recomend you buy diffuzed leds and not high brightness leds. I bought high brightness leds and you are blinded by this sign. When almost 100 leds are shining directly in your face it is like looking into the sun.
Step 2: Design Your Sign
Now that you have everything you need you can start designing your sign! You will be using excel to design your sign. You fill a cell where an led will be placed. To begin, open excel and make the all the cells squares. Then click on a cell and, using the fill tool, fill the cells to make letters. This may take a few trys to get good looking letters. Remember, this is just a rough draft, you can make it look better when you place the led on the clad board.
Step 3: Calculations for the LEDs
To begin your calculations, you need to know the voltage and amperage of your power supply. I didn't trust the power rating of my 12 volt DC power supply, so I tested it with my multimeter. Good thing I did, it was cranking out 21.5 volts. Nearly twice as much as it was rated for! The sad fact is most power supplys put out more voltage than they say. I reccomend you test your power supply so you know its exact voltage. The amperage of your power supply does not matter as long as it is above the amperage your leds are using. Now you need to know the voltage and amperage of of your leds. My leds had a running voltage 3.0-3.5 volts and an amperage of 20 mA or .02 amps. To start, we need to figure out how many leds will be in series. To do that, divide your power supply voltage by your leds maximum and minimum voltage. In my case, it was 21.5 / 3 = 7.16 and 21.5 / 3.5 = 6.14. You need to pick a value between these numbers or lower. I picked 7 so 7 leds will be soldered in series. Next we need to calculate the maximum amount of leds you can have running on your power supply. My power suppy puts out 2.5 amps max. So all you do is divide the max amps of you power supply by the amperage of your leds. The amperage of your leds needs to be in amps not milliamps. Remember there is 1000 milliamps in 1 amp. I my case it was 2.5 / .02 = 125. This means I can have 125 rows of 7 leds in series. That makes a grand total of 875 leds. You can use less than your maximum amount of leds as long as the number of leds in seris is the same. If you need help with your calculations, leave a comment and I will help you.
Step 4: Making It Real
Now we can begin placing the leds on the perf board. Using your excel drawing as a guide, put the leds legs through the holes in the perf board. The polarity doesn't matter because we will be removing the leds and marking their positions. It will thake some repositioning to get the leds to look good. When you are satisfied with the shape of you letters, begin removing the leds and marking where their legs were with a sharpie(pic 2 & 3). When you finish, transfer the design to the back by marking the other side of the hole. When you're done, it will be a mirror image of the design(pic 4).
Step 5: Cutting the Perf Board
This step is optional. You will be cutting and coloring the perf board. To cut the perf board, I used a dremel with a cut off wheel, but you can use a small toothed saw. I colored mine with a large permanent marker, which I do not recomend because It was very streaky. I suggest painting with spray paint.
Step 6: Soldering the LEDs
To begin, mark the polarity of the marked holes with a sharpie. I just put a red dot next to the positive hole. When marking the polarity, remember that the leds will be connected positive to negitive and will be the number of leds we calculated for series earlier. Next, put the legs of the leds through the proper holes. Hold the led tightly and bend the leads over so the led is securely held in place. Repeat the process with another led and snip the leds so they overlap slightly. Solder the spot where the leds overlap and repeat the process with all the leds in that row of series.
Step 7: Making "Resistors"
You will probably have some letters where the number of leds in series is greater than the number of holes for leds left for leds. When this happens you need a resistor. I didn't have a resistor so I made a "resistor". The "resistor" is a led or leds soldered the back and and wraped in tape so it emmits no light. You still need to have the same number of leds in the series and the "resistor" leds count as leds toward your led total. (example: You need 7 leds in series. You have 3 on the front so you need 4 leds as a "resistor" on the back. 3 + 4 = 7) All you need to do now is connect the sign to your power supply and you're done!
Step 8: Your Sign Is Done!
Connect to your power supply and let those leds shine. I hope you enjoyed my instructable!