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 was found on HauntForum, kudos to Niblique71 for his excellent design. I’ve

amended his basic construction techniques just a bit. The spotlights

in this tutorial have one primary change from the original, 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 bottle caps 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.

Three 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 - 1/16”,1/8”

Soldering iron, Solder and damp sponge (for keeping the soldering iron tip clean)

Wood Saw – For cutting wood base

Hack Saw – for cutting PVC

Wire Clippers

Needle nose pliers

Regular pliers

Dremel tool – Optional but makes the

job 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 shades of light 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 we are using are DC powered devices and

have a definite polarity, a positive and negative

connector. It’s important that they be hooked up

correctly in order to properly function. Our LEDs 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’s easier to think in terms of positive

(anode) and negative (cathode). Fortunately, LED

manufacturers have made it easy for us to determine

which is which… The anode (wire on the positive side)

of the LED is usually about 1/4” longer than the cathode (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 parameters for the red LEDs that we are using. Don’t let all of the

numbers throw you off. 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 emitted from LEDs - see emission wavelength

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 20 mA (milli-amperes or .002 amp) 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

burned out 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). Alternatively, too much pressure and, poof! The LED goes up in

smoke. 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 and voltage in the right range based on the power supply that 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 the parameters 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: Resistor 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. 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!

Note: If you are using multiple LEDs, be sure to use the right calculation. Don’t calculate the resistance

based on a parallel LED connection (all of the cathodes (negative leads) connected, ditto for the anodes

(positive leads)) and then hook your LEDs up in a serial fashion (cathode to anode). Each configuration

requires different value resistors.

The LEDs that have been supplied with the kits use resistors in the following table. Remember the size of

the resistor is shown by colored bands on the resistor itself. These are the colors in parenthesis after the

resistor size.

Spotlight Color (3 LEDs) 9 Volt Power 12 Volt Power

Blue, White 47 ohm (Yellow, Purple, Black) 100 ohm (Brown Black Brown)

Red 68 ohm (Blue, Gray, Black) 150 ohm (Brown, Green, Brown)

Step 1 – Constructing the spotlight housing and painting

Chances are you bought the 10 foot length of pipe at Lowe’s so begin by cutting a length of PVC pipe

long enough to house the internal components. I used a length of 5 inches in order to accommodate the

9v battery and internal components without squishing them too much but if you don’t need the 9v

capability or the switch it’s conceivable that a 2 inch length of pipe (or smaller) would suffice.

Make a mark about one inch back from one end of your PVC tube. Using the slider switch as a template,

mark the size of the hole needed to accommodate the switch on the PVC pipe you just cut. Cut the hole

you just marked. Theoretically you could “carve” the hole out using your drill and a small bit but it would

be a painful process. It’s easier to use a

Dremel tool and a straight cutting bit. Be

as precise as possible, make the hole only

just big enough to fit the switch. Chances

are you will have some gaps to fill later

but small is necessary so that switch can

be attached without large gaps.

Once the hole is cut, use your drill (or Dremel) and the smallest drill bit to drill the mounting holes for

the screws used to attach the switch to the PVC. Note however, that this is not a strict necessity… super

gluing the switch to the PVC will work just fine.

Now flip the tube over to other end.

Noting where the hole for the switch

is located, rotate the tube some

amount (I used about 1 inch (or 90

degrees) of rotation and make a mark

abut ¾” from the end of the tube.

Drill a hole at this mark big enough to accommodate the #10 mounting screw. The relationship between

the switch hole and the screw hole is not critical but think about where you would like the switch when

the spotlight is mounted on the base.

Note: do not attach the switch or the screw at this time.

Next, cut a 3 to 4 inch length of scrap 2x4 (2x3 works also). Mark a location ¾” from one end and ¾”

from the right hand side. Drill a hole at this location for the ¼” ceiling hanger. Screw in the ceiling

hanger.

Paint the PVC pipe, the wood base (with the ceiling hanger installed) and

the two bottle caps with the color of your choice.

Throughout the remainder of this how-to, the PVC pipe will have a “top”

and “bottom”. The top is the end of the PVC closest to the hole for the

switch and the bottom is the end closest to the hole for the mounting

screw.

Step 2 – LED setup

Drill six small holes (1/16” bit or smaller) into one of the bottle caps. It may be hard to see from the

photograph but the holes are spaced at approximately 60 degrees around the bottle

cap with one hole closer to the center and one hole closer to the rim. If the two holes

are connected with a line, the line will go through the center of the bottle cap. The

holes should be very small, just large enough to accommodate the leads of the LEDS.

They should be drilled so that both of the LED leads fit comfortably into the holes

without having to spread the leads too wide when inserting the LEDs. Insert each

LED into a pair of holes with the anode (longer lead) into the hole closest to the

middle of the bottle cap and the cathode (shorter lead) into the hole closer to the

rim of the bottle cap. Insert all three LEDs in this fashion. If you so desire, put a spot

of superglue on the bottom of each LED to secure it to the bottle cap. This will make

working with the leads a little easier.

After the glue dries, twist the three anode leads together. These are the long

leads of the LEDs and should be closest together if the LEDs were correctly

inserted into the bottle cap. Temporarily bend the cathode leads over the edge of

the bottle cap, just to get them out the way. Solder the three twisted anode leads

together

Now take the two resistors and twist two of the leads together. It doesn’t

matter which ends get twisted since resistors do not have a polarity. Take

the twisted resistor leads and twist those around the twisted LED anode

leads (yes, this is a twisted process). Solder the five twisted leads together

then, when cool, cover with a piece of heat shrink tubing.

(This picture shows the resistor leads soldered to the three LED anode

leads.)

The next step is the trickiest part of the entire process.

Move the three LED cathode leads around until they can

be joined. You may be able to twist the three together or

it may take a couple of solder operations to get them all

nicely together. As you are moving the cathode leads

around make sure that they don’t touch the metal of the

anode leads that was just soldered. This will short out the

LEDs and prevent correct operation. Solder these leads together.

Step 3 – Switch Construction

Strip ¼” of insulation from both ends of each of the three six

inch lengths of wire. Slip the wires into the square switch hole

on the PVC pipe with one wire coming out of one end of the

PVC pipe and the other coming out of the other end.

Now look at the bottom of the slide switch. If you’ve used the

Radio Shack SPDT switch there will be three connectors on the bottom. Other

workable switches may have only two. On the Radio Shack switch solder one of the

wires to the middle connector then solder the other wire to one of the end

connectors (it doesn’t matter which one). When the soldering is complete, use heat

shrink tubing to cover both soldered connectors.

Step 4 – Attach the LED Cathode Leads to the Switch

Take the wire coming out of the “front” of the PVC tube. Remember, the

front is the end that is closest to the square switch hole. You are going to

twist this wire together with the LED cathode leads (the ones that don’t

have the resistors connected to them) but before you do, slide a piece of

heat shrink tubing down onto the wire going to the switch. Solder the

cathode leads and the switch wire together. After the joint cools, slide

the heat shrink tubing up over the joint and shrink it using the heat gun.

Step 5 – Power Management

Time to attach the power leads. Take the other bottle cap and drill a small hole in the middle, just large

enough to slide the wires from the 12v pigtail through. Leave about 3

inches of the pigtail out of the hollow end of the bottle cap. In order to

provide some strain relief, tie a knot in the other end of the pigtail leads

as close to the end of the bottle cap as possible. There are two wires

coming out of the pigtail that you just

slipped through the bottle cap. It may look like a single wire but close

inspection will show two wires that can be separated by pulling them

apart. Note that the plastic case of one of the wires has a white stripe and

the other is all black in color. The wire with the white

stripe is the positive lead coming from the 12v pigtail.

Put this wire all the way through the PVC pipe from

the “back” so that it comes out the front of the PVC.

This lead will be attached to the “12v” resistor. Which

one is the 12v resistor? It’s the one that you identified

back when doing the LED calculation for the 12v

power supply. In the case of the white and blue LEDS,

this will be a 100 ohm resistor with the color code

brown, black, brown. That is the resistor to which the

12 volt positive power lead (the one with the white line) will be soldered. Remember to slip a piece of

heat shrink tubing onto the power lead before soldering.

Take the 9 volt battery connector and separate the black and red leads. Strip both ends leaving about ¼

inch of bare wire. Solder the red (positive) lead to the third 6 inch piece of wire (the one you haven’t

used yet). Slide a piece of heat shrink tubing over the end of the 6

inch wire and shrink it down over the joint you just soldered. Now slip

the free end of the 6 inch wire through the back of the PVC tube all

the way through to the front. You will now solder the free end of this

wire to the free lead of the other resistor. In the case of the blue and

white LED kits, this is the 47 ohm resistor with a color code of yellow, purple, back. Before soldering the

wire, slip a piece of heat shrink tubing on the end of the wire for covering the joint after you solder it.

There should now be three free wires at the back end of the PVC

pipe, an all black wire from the 12v pigtail, a black wire from the

9v battery connector and the wire that is attached to the switch.

Trimming wires as necessary to shorten them as much as possible,

solder the ends of these three wires together. Don’t forget the

heat shrink tubing to cover the joint.

Step 6 – Putting It All Together

Congratulations, you’re done with twisting, soldering and shrinking, now it’s time to test. Attach a 9v

battery to the battery connector. If the lights don’t

come on immediately, slide the switch to the other

position. You should be rewarded with a very nice light!

Next attach a 12v power supply to the pigtail. Be sure

the power supply has its positive side as the middle pin of

the connector with the negative side as the metal ring on

the outside. Switching polarity will not light the LEDs and

will eventually damage them.

If everything works correctly it’s time to put the spotlight together. As you may have noticed, the bottle

caps just won’t fit in the PVC. Partly right; they won’t fit without a little

encouragement. Use your heat gun to heat up the front end of the PVC pipe

from the end of the PVC back about 1.5 to 2 inches. When it begins to get hot,

and a little soft, push the front bottle cap with the LEDs down into the PVC. Push

slowly and if you encounter too much resistance, heat

the PVC a little more. If you push too hard you may

split the PVC. This is not the end of the world, or the spotlight, but it certainly

isn’t as pretty as it should be and may compromise the operation if things

ever get wet. Push the bottle cap far enough down the PVC pipe so that the

pipe covers the LEDs by ¼ inch to ½ inch.

Before you insert the back bottle cap, take the #10 screw and working from the inside of the tube, insert

it into the hole that was drilled in the back of the PVC tube. Just for now,

attach the wing nut so that the screw doesn’t fall into the tube. Also, if you

plan to run the spotlight from a 9v battery, now would be a good time to

attach the battery and put it in the PVC pipe.

When you are ready, heat the back of the PVC

pipe like the front and when it gets warm enough,

insert the bottle cap. Important Note: when

inserting the back bottle cap, do not insert the

cap all the way into the PVC pipe. Leave half of the bottle cap emerging from

the back end. This will allow you to pull the bottle cap out later when you

want to remove or replace the 9v battery.

Next, take the two very small #2 screws and attach the slide switch with

them. These screws are optional. If you choose, a couple of good shots of

gel Super Glue will also hold the switch quite adequately.

Remove the wing nut from the #10 screw and put on one of the #10 flat

washers. Put the screw stem through the eye of the ceiling hanger that’s been

screwed into the base, slide on the last washer and then tighten it all down

with the wing nut. If you have any small holes, like around the switch or in the

back where the 12v pigtail goes into the back bottle cap, use some of the gel

Super glue to fill them.

One final note: What if there’s a 9v battery inside and you’ve attached the

12v power supply? The good news that it won’t hurt anything. The bad news

is that the 9V battery will eventually deplete its charge. The electrical

engineers in the audience will undoubtedly implement a system with diodes

and transistors that would turn off the current from the 9v circuit if the

current was flowing through the 12v circuit. Some folks might add another

switch to turn off the battery when hooked up to 12v. I took the simplest

route… if I plan on running from a 12v power supply, I will take out the 9v

battery! Simple but admittedly unsophisticated.

What to do if things don’t work?

First go back through the instructions, step by step, and make sure that you used the right wire in the

right place. Make sure that the LEDs have the long wires (anodes) twisted together and that you haven’t

mixed up the wires. Next make sure that the wires you soldered are really still together. Sometimes it

can look like you have solid joints but they came apart as soon as you put on the heat shrink tubing.

Wiggle the wires and even tug gently on the ends. If something feels loose or comes apart, re-solder it.

In most cases, a walkthrough of the instructions will show you where you switched polarities or mis-

wired something.