Introduction There are many tutorials available on how to make your own LED spotlights. I ve looked at quite a few and the one I like best is found on HauntForum. The author is Niblique71 and I ve used some of his illustrations in this tutorial. The spotlights in this tutorial have one primary change from Niblique s, the ability to run from either a 9v internal battery or an external 12v supply. My haunt has a few places where running wiring is either not feasible or not aesthetically pleasing, so running the spotlight from a 9v battery is advantageous. The other change is the addition of an on-off switch for turning the spotlight on/off in order to conserve battery life. Parts List Each of the items below is per spotlight One 5 inch long section of 1" thin wall PVC pipe Be sure to get the thin wall and not the thicker Schedule 40 PVC. In Denver, I found the thin wall PVC at Lowes but Home Depot did not have it. Two Plastic bottle caps Either Coke or Pepsi products work fine and it doesn t matter whether you buy 2 liter, 1 liter or 20 oz bottle, the caps are all the same size. Additionally, even the black bottlecaps come with advertising these days so I paint them all as a result color doesn t matter. Three 5 mm LED (Light Emitting Diodes) There is a universe of choices for LEDs these days, colors, sizes, intensity, view angle, etc. I ve limited my builds to 3 LED spots but you can fit at least 5 five mm LEDs on a bottle cap and maybe even 7. I ordered my LEDs from superbrightleds.com in four different colors: Blue (RL5- B4630), Red (RL5-R8030), White (RL5-W8045) and Ultraviolet (RL5-UV0430-400). Two Resistors (one for the 9v battery and the other for the 12 v power supply) Resistor size is based on number of LEDs, LED parameters (required current) and LED configuration. I bought mine at Radio Shack. More on this later. Small slide switch I used a SPDT submini slide switch from Radio Shack (275-0409). This was a pricey item (about $1.60 per switch) and you can probably find them less expensive on the Web. One 9v battery connector One 2.1mm female plug for the 12v power supply Another pricey item, about $2.00 per plug. If you plan to run a 12v power supply, you will also need the male jack to match (not included in the kit) but 2.1mm is a very common size. Many wall wart power supply plugs will fit. One #10 ¾ round head machine screw Two #10 flat washers One #10 wing nut Two #2 round head wood screws (optional) These little screws can be difficult to find. Don t even bother with the big box hardware stores (Home Depot, Lowe s). I had the best luck at Ace hardware in their specialty screw cabinet. In
any case, these screws are not mandatory. They are used to attach the switch to PVC pipe and a good shot of Super Glue will do just as well. One ¼ by 3 Eye Lag Screw (aka Ceiling Hanger) When I asked the Home Depot guy to show me the eye lag screws, I was met with a blank stare. However, when I asked for the ceiling hangers, he knew exactly what I needed. Gel Super Glue I used Super Glue to not only hold components in place to also to fill any little holes or gaps. The best product for this is the Control Gel super glue by Loctite. Regular super glue will just run into the hole. Two 6 lengths of 22 Gauge Solid Hookup Wire Jacket color doesn t really matter. I bought mine at Radio Shack in a package that contained three 30 foot rolls in red, black and green jacket color. One 3 length of 2x4 This is for the spotlight base Black (or other desired color) spray paint Heat shrink tubing ¼ and smaller diameter
Tools List Safety glasses Hand drill Drill bits - 1/8, ¼ Soldering iron, Solder and damp sponge Wood Saw For cutting wood base Hack Saw for cutting PVC Wire Clippers Needle nose pliers small and large Small Phillips screwdriver Small regular screwdriver Dremel tool Optional but makes the job much easier. Hot air gun Required - This is important in order to make the bottle caps fit inside the PVC and to shrink the heat shrink tubing around the soldered joints. Wire strippers Multi Meter (not necessary but helpful) Sandpaper
LED Tutorial LEDs are amazing little devices and are becoming the light source of choice in many applications including brake lights for cars, traffic lights and even home lighting. They can be manufactured to produce many hues and LEDs of different colors can be combined and controlled to produce nearly any color. There are a few things that you should know about LEDs before you begin working with them. The first is that LEDs are DC powered devices which means that they have a definite polarity. DC powered devices have positive and negative, meaning it s important that they be hooked up correctly in order to properly function. The LEDs that we are going to work with have two wires coming out of the base. The names of these wires follow the old tube convention (you have to be over 40 to even remember vacuum tubes!), one is called the anode the other the cathode. For our purposes it is easier think in terms of positive (anode) and negative (cathode). Fortunately, LED manufacturers have made it easy for us to determine which wire is which The wire on the positive side of the LED is usually about ½ longer than the wire on the negative side. There a number of ways to define the operation of an LED depending on what you need to do. The example sheet below shows the LED parameters for the red LEDs that we are using. Don t let all of the numbers throw you off, however, in our case we are most concerned about color, power requirements and viewing angle. Part Number: RL5-R8030 - Super-Red LED (AlGalnP) absolute maximum ratings: (TA=25 C) PARAMETER SYMBOL RATING UNIT Power Dissipation PD 80 mw Continuous Forward Current IF 20 ma Peak Forward Current (1/10th duty cycle, 0.1ms pulse width) IFM 50 ma Reverse Voltage VR 5.0 V Operating Temperature TA -40~+85 C Storage Temperature TSTG -40~+85 C Reverse Current (VR=5V) IR 10 µa Lead Soldering Temperature (3mm from body) 260C (for 3 seconds) optoelectric characteristics: PARAMETER SYMBOL MAX TYP UNIT TEST View Angle of Half Power 2ø1/2 30 Degree Forward Voltage VF 2.6 2.2 V IF=20mA Peak Emission Wavelength ÿ P 630 nm IF=20mA Luminous Intensity IV 8000 mcd IF=20mA
Dimensions in millimeters (inches) Spectral Graph
Note: photo is to show beam pattern, digital camera and monitor cannot accurately reproduce the pure colors emmitted from leds- see emmission wavelength Viewing angle provides information on the brightness and size of the light cone for a given LED. Basically, the viewing angle tells you at what angle at which the brightness of the LED is cut in half. This also tells you the width of the illumination zone (at 50% brightness) at a given distance from the light. In the extreme, a laser has a very small viewing angle; even at 100 yards, the point of light is nearly the same size as at 1 inch from the device. In our case, we want an LED that will have a larger zone of
illumination so that our props are lit correctly. Viewing angle for the red LED is 30 degrees. So, at 3 feet from the red LED, the illumination zone, at 50%+ brightness will be 1.6 feet across. The effective size of the illumination zone will be larger but the light intensity will fall off outside of the 1.6 foot diameter. Here s the math Viewing Angle (VA) = 30 degrees ½ of VA = 15 degrees At 3 feet away from the LED, the 50% illumination zone of a single red LED will be: LED Viewing Angle = 30 2*(3 feet * tangent 15 degrees) = 1.6 feet Color is obvious (pink isn t usually a great Halloween color!) but what about power? Looking at the parameter sheet, you will see that the forward current is 20mA (milli-amperes or.020 amperes) and the peak current is 50 ma. This means that the normal current required for this LED is 20 ma and the peak current is 50 ma. You won t want to power your LED at more than 50 ma for very long unless you like fried LEDs! Just think of current like the water flow through a pipe. In this case, the LED requires just a tiny trickle of electrical water to make it work, at least compared to those old AC spotlights you used to use. The other interesting power parameter is Forward Voltage. This is the voltage drop across the LED. You can think of voltage as the water pressure required to provide the water current through the LED. If you don t have enough pressure (voltage) the required water current won t be sufficient to water the plants (power the device). In our case, the forward voltage for the red LED is 2.2v. There s a trick for making sure that you keep the electrical current in the right range based on the voltage you are using. This is done by using a resistor in line between the power source and the LED. The resistor size depends on two things, the voltage that you will use to provide the required electrical current and the average current needed to power the LED. Rather than get into the mathematics, look instead at this website: http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator. This site allows you to input the parameters for your LED application and calculates the correct resistance value to use to limit the current to the LED device.
For example: Our LED spotlight will use three LEDs connected in parallel, each with a forward current of 20 ma and a forward voltage of 2.2 volts. LEDs in parallel: Supply Voltage 9 VOLTS Voltage Drop Across LED 2.2 VOLTS Desired LED Current 20 MILLIAMPS How many LEDs connected 3 Calculated Limiting Resistor 113.33 OHMS Nearest higher rated 10% resistor 120 Ohm Calculated Resistor Wattage 0.408 WATTS Safe pick is a resistor with power rating of 0.68 WATTS Plugging this into the resistance calculator gives a resistance value of 113.33 ohms. Unfortunately, they don t make 113.33 ohm resistors so we ll go with the next largest size, in this case, 120 ohms. One other note: For our purposes, resistors generally come in ¼ (0.25) watt and ½ (0.5) watt packages. The calculator recommends a 0.68 watt resistor but we ll be just fine using 0.5 watt resistor. But wait, you say, our spotlights will be powered by one of two different power supplies, either a 9 volt battery or a 12v supply. Doesn t that mean we will need two resistors? You would be right we will use a 120 ohm resistor for the 9 volt battery and a 180 ohm resistor for the 12 volt supply for our red LEDs. The white and blue LEDs will require different resistors. Plug in 12 volts into the resistance calculator and try it out. Remember to use the LED parallel section or you will get the wrong answer!