Making a LED Spotlight
Posted by Willuknight
Yesterday I finally managed to assemble the parts I need, and got around to making this awesome 375,000 mcd Molex powered spotlight. I’m even
going to show you how to make it!
1) 3x LEDs, the brighter the better.
I used 125,000 mcd LEDs which draw 3.2 volts. Have a look on eBay, or at a large electronic retailer. These LEDs cost me $15NZ for 10.
2) Resistor.
The type of resistor you use depends on what LEDs you buy, and their specifications. I used this calculator to work that i needed a 100omh resistor. Remember that the resistor you use depends on the LED and the power source - and that if you choose the wrong one, you will damage your LEDs. The ones I bought cost $0.28NZ for 5
3) Molex Connecter.
You’ll only be using 2 of the connecters in the Molex, Yellow (12v power) and
Black (Ground). You can get Molex connecters from a computer store or electronic
parts specialist. Make sure you get a male connecter (has pins, rather then
sockets). DSE charged me $1.20NZ for a packet of both Male and Female connecters.
4) Wire.
Double stranded wire is the best, because it keeps it together. The length depends on you, it depends on how far you want to place the spotlight from the PSU’s connections. I used 1meter, because I wanted to be able to place the spotlight on my desk as well. Prices are about $0.50 - $1 per meter (NZD).
5) Electrical tape.
Just pick this up from wherever. It’s main function is to make a nicer finish, and cover up all the exposed wire. I got a roll for $0.70NZ.
And last of all, you’ll need something to house the led in. Matchboxes, other small things are all possible, but i just made my own box out of cardboard. The advantage of this is that you can make it completely the way you want.
TOOLS:
Essential:
Soldering Iron
Utility Knife
Stuff that will make making this a lot easier:
Wire Cutters
Mini Screwdriver (for prodding things)
Glue gun (for affixing things)
Helpful:
Permanent Markers - Red and Black
Soldering Station
Step 2) Arranging the LEDs and other Preperation
Assuming you’re using cardboard as a base, this part is pretty easy.
1) Use the utility knife to cut out a small square of cardboard that is large
enough to fit all the LEDs on the comfortably.
2) Cut a small slit where you want each led to sit (see yellow on the picture). Make sure that you’ve left enough space so that the LEDs can be flush against
the cardboard, without overlapping on each other. If you muck up this, you’ll
have to start again with another piece of cardboard.
3) Stick the LEDs legs through the slits and turn the entire assemble upside
down
.
4) Once that is done, take your utility knife and trim the plastic off both
ends of your wire. About 1 cm should be enough. It might pay to mark side as
positive and the other as negative with markers. The last thing that you want to
happen is to accidentally switch the wires and wire up + to - when you’re
supposed to be wiring + to +.
Step 3) LEDs Legs
There are two ways to check what orientation a leg is.
A) LEDs are always sold with their legs being different lengths. The Positive leg is always longer then the shorter negative led. Of course once you start to cut the legs down to make everything fit, then this telltale goes.
B) If you look at the sides of the led bulb, one side is flat (or blunt). That side is negative.
We’re hooking the LEDs up in a series, which means
that the current flows down one led, and into the next (see diagram).
TIP: If you have a marker pen, then I find that at this stage it
really helps to mark the legs of the LEDs so that it’s easy to tell - from +. As
you can see in the first picture, I’ve marked the - legs with black.
1)
Cross the legs of the LEDs, so that they are Positive to Negative. At this
point, you may wish to trim the legs so they are not so long. I left mine longer
then usual so that if I wanted to, I could disassemble the spotlight later.
2) After the legs are trimmed, bend the legs to make sure that
they’re all overlapping where they are supposed to be, and that none of them are
touching where they shouldn’t. I found using a mini screwdriver as an angle
to bend the legs over, really helpful.
Step 4) Soldering
Once the legs are trimmed and bent correctly, double check that the LEDs are in series and that the current direction is correct (i.e. positive to negative). As you can see in the picture, Led 1 is hooked up to Led 2, Led 2 is hooked up to Led 3, Led 3 is connected to the power source and then back to Led 1.
TIP Tin the ends of what you want to solder, by heating up the wire, then applying solder. If the legs are resting apart, put solder on both sides, then push together (with a mini screwdriver or something), heat the solder until they melt together and then remove the heat.
1) Solder the legs of the leds together.
2) Solder the resistor to the + leg of led 3.
3) Solder the wire to the panel. As you can see in the bottom
left picture, I’ve marked both the wire and the led leg with black marker - to remind me that they are negative current.
4) Solder on the Molex pins to the other end of the wire.
The easiest way way to do this is insert the trimmed wire into the pin and then
squeeze the gripper at the end of the pin down on the wire to hold it in
position. These are the easiest components to solder.
Step 5) Testing
Now that all the wires are connected and soldered together it’s a good idea to test the connection, so go ahead and plug it in and try it out. MAKE SURE YOU PLUG THE MOLEX CONNECTER INTO THE RIGHT PINS!!! The positive lead should plug into the YELLOW wire on the Molex connecter and the negative lead into the black lead immediately beside it..
Your spotlight should be fully functional at this stage, mine
was. If your light isn’t working, double check that its not short circuiting
somewhere and that nothing is touching (i.e. conducting current) that shouldn’t
be. Also check the wire to make sure that it’s wired up correctly. Lastly, try
unplugging the Molex pins, turning them around a bit and reinserting them.
Step 6) Stabilizing
Now that everything is working, unplug it and we’ll finish off
the project
1) Use pieces of electrical tape to prevent the wires from accidentally joining and short circuiting. I had a bit of a wire loop, with the positive lead passing directly over the led connection. As you can see in the picture, by using a piece of tape, I was able to separate the top wire from the bottom wires and ensure they didn’t accidentally bump together.
Alternatively you could use a glue gun to do this - which would probably be a LOT more stable. I didn’t do this, because as I said before, I wanted to make it so that i could take it apart at a later date, if I needed too.
Step 7) Making the Spotlight stand
1) Get a strip of cardboard about 2cm or so wide - or wide
enough so that the top of the box won’t press against your components.
2) Wrap this strip around the edges of the component platform, so that it forms a box shown below. You may need to trim the strip so that it’s a perfect match. Once the initial folds are in the cardboard, take it off and crease these folds again just make it a bit more square. Then put it back. As you can see in the 3rd picture, i made a mark on the side and top to indicate where its supposed to line up.
3) After you’re sure about the measurement and that its fitted correctly, use a glue gun to glue the sides of the platform to the walls of the box. Do this one side at a time, DON’T try and glue all the walls at once. When all of the walls are glued to the platform, put a bit of glue along the side where the walls join (top of picture 2 and 3).
Finishing Up
Put some more electrical tape around the box to hold the wires
firmly in place and to cover up the rather grungy looking cardboard. I made a
cardboard bottom for the piece with two slits in it (for the wires to go
through) which held those in place - and then wrapped it up in tape.
Here are a few photos from my finished project:
Categories: Guides, Misc.