Copper is a really good looking metal. It's rarely used for domestic applications, such as light fixtures. Almost everything, that is made out of metal these days is made out of stainless steel. I'm tired of it, so I thought: why not make something different. Something unique.
This instructable will show you how to make a very energy efficient and unique light fixture for illuminating your paintings or photographs.
I will also show you how you can make it light sensitive, so that it automatically turns on at night.
Step 1: Materials
- A copper tube. These are widely available. You can get them at Home Depot and other stores that sells plumbing supplies. They're available in many different diameters. Try not to get one, that is too thin, as it will make it difficult to wire up the LEDs. The one I used was 1.5 centimetres (0.59 inches) in diameter, and I don't recommend using a smaller diameter than that.
- LEDs. For this type of project, you'll definately want warm white LEDs. The normal white or cool white LEDs will often be more bluish in their light, and you don't want a bluish light on your painting or photograph. In the next step, I'll show you some of the many LED possibilities. The quantity depends on your needs and the length of the tube. I used 9.
- Some enemaled copper wire a.k.a. magnet wire. It's a good idea to use two different diameters, so you can easily identify the polarity.
- Resistors. The quantity and value depends on the type of LEDs and how many you use. I will show you how to calculate the value of the resistors in step 3.
- Two screws for mounting your fixture on a wall. Brass screws are the preferred ones for this project, because they almost have the same color as the copper tube.
- Some hookup wire to connect it to your power supply.
- Some thinner hookup wire to connect the two ends of the tube together.
- Heat shrink tubing. You'll need different diameters of it.
- A sheet of ordinary paper.
Step 2: Choosing the Right LEDs
The 4.8mm wide viewing angle LED. This LED has a wide viewing angle, which is great for this project, but it's not bright enough to properly light up a painting or a photograph.
The classic 5mm Ultrabright LED. This LED is bright, which is great for this project. The problem with this LED is that it has a narrow viewing angle, so it will not distrubute the light uniformly, so there is a risk of getting light "dots" on the painting or photograph, that you will be illuminating.
The wide viewing angle SuperFlux LED. This LED has a wide viewing angle like the 4.8mm LED has, but as with the 4.8mm LED, it is not bright enough for this project.
The 8mm "StrawHat" Ultrabright LED. This LED has a wide viewing angle, and unlike the SuperFlux and the 4.8mm LED, It's very bright. It's the perfect LED for this project. The only problem it has is that it heats up quickly, but that's not a big problem in this case, since the LEDs will be hanging in mid-air. I chose these LEDs for the Copper Style LED Painting Illuminator.
The pictures below shows all the four LEDs mentioned above. There are also a couple of pictures showing the difference between a cool and a warm white LED from the same manufacturer.
Step 3: Calculate the Resistor Values
In this step, I'll show you how to calculate the value of the resistors. Before you can calculate the value, there are three things that you need to know.
The forward voltage of the LED(s). In datasheets this is often marked as Vf. For white and warm white LEDs, this is usually 3.4 to 3.6 volts.
The forward current of the LED(s). In datasheets this is often marked as If. The forward current varies a lot from LED to LED. LEDs that has a brightness of 1000mcd to 20000mcd usually has a forward current of 20mA. However this is not always the case. You should always check the specs of your LEDs.
The supply voltage of the intire circuit. I used a 12V wall wart adaptor.
I use ledcalc.com to calculate the resistance of the resistors.
To calculate the resistor value, simply type in the forward voltage, forward current, the supply voltage and how many LEDs you want. The calculator recommends a 56 ohm resistor when using two 100mA LEDs in series with 12V supply voltage.
Note: the resistor values shown in the schematic below are for the 5-chips 100mA LEDs that I use in this project only. If you're using different LEDs than I do, you should use ledcalc.com to calculate the proper resistance.
Step 4: Prep the Copper Tube
Once you have sawed off the desired length of tube, you can start drilling the holes in your tube. Start by drilling the two screw holes. I drilled my holes one centimeter from the two ends of the tube.
After you've drilled the screw holes, start drilling the smaller holes for the LEDs. I drilled my first "LED hole" 1.5 centimetres from the screw hole (2.5 centimetres from the end of the tube).
Next, you'll need to do some math. You'll need to calculate how far the holes for the LEDs should be from each other. The spacing between the two outer LED holes is 40cm in my case. This is how you can calculate it: Take the number of LEDs, you want and subtract one by that number (in my case 9-1=8), then take the distance between the two holes (in my case 40cm) and divide it by that subtracted number.
The reason why, you'll need to subtract one by the desired LED quantity is that if you measure the distance between your outer two LED holes, the first hole is going to be at "0cm" at you tape measurer or whatever you use to measure, and last hole is going to be at "40cm". So if you want say 8 LEDs on 40cm and you just use this calculation: 40 divided by 8 is 5, and you start drilling the holes with 5cm between each hole, you'll end up having 9 holes, because the first hole is at "0cm". So always subtract one by the desired number of LEDs.
The result of that calculation is 5 in my case. That means that the distance between each LED hole should be 5cm.
Use a permanent marker to mark up, where you want to drill the holes.
Step 5: Solder the LEDs and the Copper Wires Together
Before you start cutting the wires, you should know how far from the tube you want to have the LEDs hanging. I found out that 30 cm was a good distance for my painting. Keep in mind that the wires should be long enough to come out of the end of the tube. I reccomend making the wires a little longer than you want them, because then, if they are too long, you can always cut a bit off.
I used two different diameters of enemaled copper wire to make it easier for myself to identify the polarity. I used the thicker wire for the positive connections and the thinner wire for the negative connections.
There are three ways to find out which LED lead is the positive (the anode) and which one is the negative (the cathode). 1. Almost every through through hole LED has a shorter lead, which is the negative and a longer one, which is the positive. 2. Most through hole LEDs have a ring at the bottom of their housing, and the ring has a flat side, and the lead closest to that flat side is the negative. 3. If you have a clear LED, you can see that there are two pieces of metal inside it. The biggest piece of metal is usually the one that connects to the negative leg of the LED.
I used a drill to twist the wires.
Always remember to slide the heat shrink tubing over the wires before you solder them together with the LEDs.
I started with the two outer LEDs which had the shortest wires.
Follow the instructions on the pictures below.
Step 6: Mount the LEDs
Another thing, that you need to do is to cut two pieces of wire, that are a little longer than the tube. This wire will be used to connect the two ends of the tube together.
Bacause I used 9 LEDs, I had 4 pairs of wires coming out at one end of the tube and 5 pairs coming out of the other. If the wires coming out of the tubes differ in length, you'll need to trim them, so they all have the same length.
Further instructions can be seen in the yellow boxes on the pictures below.
Step 7: Wire It Up
There are a lot of pictures in this step. The ones that have yellow boxes contains instructions. Move your mouse over the boxes to view them
The pictures will guide you through the process.
Step 8: Make It Light Sensitive
Here is a video showing the Copper Style LED Painting illuminator with this light sensor in action.
The sensor has been adjusted so that when the ceiling light is turned off, the light bar turns on.
Note: from the the point of 00:22 and to 00:48, it's flashing because I'm waving a small flashlight over the light sensor.
Here is what you need to make it.
- An LDR. Also known as a photoresistor, photocell or CdS cell.
- An LM358N low power dual OpAmp.
- An 8 pin DIP socket for your OpAmp. This is not strictly neccesary, but it's reccomended
- A 10kohm resistor.
- A 1-10kohm resistor. This resistor is used to limit the current going through the base of the transistor. The resistance of this resistor can be from 1-10kohm. The transistor doesn't care.
- A 10kohm trimmer potentiometer. Can also be a normal potentiometer.
- An NPN transistor. This project just requires simple on/off switching, so almost any NPN transistor will do. Here are some examples of some the transistors, you can use: 2N2222, BC337, S8050, BD139 and many others. Just check your transistor's datasheet to make sure, that it can handle the power needed for your fixture. My circuit uses a little less than 500 milliamps, so I used a BC337 because I already had some lying around.
- A small PCB to solder all the components onto.
You can control at which brightness it turns on by turning the potentiometer.
Step 9: You're Done
Here are some more pictures.