Introduction: Capacitive Copper Cube Lamp
Hello and welcome! In this Instructable we will learn how to create either a standup or hanging touch sensitive LED lamp made from custom made circuit boards. We will incorporate a novel application of stained glass style soldering techniques to assemble our lamp, and use an Arduino with some very simple and customizable code to control our LED's. The simple geometry of the cube makes this a great first step to learn the techniques before moving on to more interesting arrangements and applications, so let's get started!
Step 1: Tools and Materials
- 6 copper pcb's
- programmable LED's (www.coolneon.com total control lighting pixels highly recommeneded)
- arduino (most any will suffice)
- copper wire
- large gauge solder for stained glass style soldering
- copper foil roll/strips
- 100watt weller soldering iron with chisel tip (regular $10 radio shack ones will NOT work)
- paint brush
- wire strippers
- electrical tape
- drill press
If you are lucky enough to live in the bay area, I highly recommend Cradle of the Sun in San Francisco for all of your large gauge solder, foil, flux, and even your weller, the owner is extremely kind and informative. Otherwise, everything can be acquired online and can be done at home with a tiny bit of practice and the oh so fun trial and error. Now that we have everything we need, let's continue.
Step 2: Designing Your Circuit Boards for Capacitive Touch
Now we get to have some fun! Your aesthetic is completely up to you and your application, but there are a few things to keep in mind before simply soldering a pcb or other conductive material to an arduino and trying to run some code, specifically, the size and shape of your touch sensitive areas.
First, what may be extremely obvious to some but maybe not others, isolate your touch sensitive areas from the rest of the object. This can be done very easily by incorporating a small island of copper into your design, to act as your "button." This is the area that we will hard wire to our arduino.
If your touch sensitive area is too large, something extremely fun and interesting happens, but this can also be the cause of many headaches and is not a desirable outcome for this project. A capacitive touch sensor with too large a surface area WILL DETECT WITHOUT TOUCH. This is very cool, and can even be utilized for this or other projects, but is a much buggier process to troubleshoot. It may be worth pursuing if activating an object by simply placing your hand a foot above it excites you, I know it gave me quite a bit of fun.
Now that you have a design in mind, the next step is to make circuit boards ready for assembly, there are a few ways to go about this, one detailed in a previous Instructable of mine here:
Or if you happen to have access to awesome cutting edge machinery that can make pristine boards for you, such as the Othermill from Othermachine, definitely go that route, I'm jealous.
Once you have pretty boards all ready to go, continue on to the next step.
Step 3: Assemble Your Boards
Once your boards have been made, take them over to the drill press and drill holes big enough to poke a copper wire through in the area where your sensors will be. Then, simply cut a length of wire, poke it through the hole and solder it in place. After all your boards have gone through this it's time to move on to learning stained glass style soldering!
First, take your roll of copper foil, and wrap the edges of your boards with the foil, one continuous piece per edge, keeping the majority of the foil on the inside fiberglass portion of your board, an ideal width of foil to fold over the front face would be ~1/2 a centimeter, to reduce the amount of solder needed to cleanly attach the two boards.
The technique for stained glass soldering is a bit more involved than regular soldering, but is really not that difficult and can be done well after some simple practice. Some cheap or small pcb's would be a good training ground before moving with confidence to your pretty cube. Fluxing the area first is absolutely necessary to allow the solder to flow smoothly into your desired cracks, and a stable hand while pulling the iron towards yourself, and over the solder and crack, will give good results. The good thing about solder is that it can be easily reshaped, smoothed, or removed with a desoldering braid or suction. The diagram above attempts to illustrate this, but a video will be better and edited in soon.
Now grab your boards, and some tape, and slowly build your cube by taping each face together, making small adjustments here and there to keep your edges flush and without gaps. Plug in your Weller soldering iron to heat up, then position your cube in such a way that the edges to be soldered first are as level with earth as possible, use makeshift jigs or household items for this, I personally just use an open cardboard box. Having your seams level is extremely important for success in soldering cleanly and without ugly drips or splatter. When your iron is hot, tinned and ready to go, grab a small brush to flux your first seam. Start first with the easier inside seams of the cube, which of course is concave and unwanted drips are less of an issue. Brush the area with your flux, then follow up with spot soldering near your corners first, do not solder an entire seam only to realize something is out of whack elsewhere.
Hopefully after spot soldering all your key areas inside the cube and checking every side is in alignment, you will seal the deal and your unfinished seams. Finish the process by soldering all inside seams with a heavy bead, you now have a very sturdy cube. This is also the point where you must decide whether your cube is going to be sitting or hanging, which will dictate whether you absolutely need to add a sixth side to the cube or not. If you have a tabletop area in mind, leaving a face open on the bottom can make initial troubleshooting or adjustments easier. If you want to completely seal the cube after you feel confident all of your parts are working and stable, using the 4 necessary wires to hang the cube can be a good solution, but first, lets attach our arduino and LEDs to our sensors, and get this cube up and running.
Step 4: Arduino and LED Installation
Now that we have our cube body ready, let's get going on the guts that make it work. Decide on how many LED's you will be using to light the selected areas of your cube, snip this amount from the string you purchased, and save the remainder for future projects. The example code will assume 25 LED's and you can change this later if need be.
First, let's work on the capacitive sensors. Below is the original capsense arduino tutorial which gives the best introduction on how the understand and build capacitive sensors, it includes the necessary capsense library, and good example code to play around with. I'll also include a diagram I found helpful on another instructable (https://www.instructables.com/id/Capacitive-Touch-A... to help you understand how truly simple the schematic is, keep in mind the pins shown are just a suggestion.
Once you have your resistors running to your selected input pins and common pin, make sure they are working properly by running the basic example code for this library, open up the serial monitor and make sure you are getting a reading when touching the input side, take note of the values generated at baseline and while the input wire is touched. Once you are sure you have the arduino side of things working properly, attach your circuit board sensors to each individual resistors input side. Double check that the sensors are getting good readings after attaching the circuit boards, and note the likely changes to your serial monitor values so that you can use these values in your code later.
Now that we have working input for our cube, let's use it to generate some cool LED animations! Let's start with how to connect your LED's to your arduino. This is all assuming you have acquired some Cool Neon total control lighting pixels, which are very reliable and superior to many alternatives, are not subject to problems due to voltage drops over long lengths of connecting wire, and support a variety of controllers sold by Cool Neon. Here I must mention another invaluable tutorial made possible by Chris De Vries, who made a great arduino library for us to use, and explains in great detail how to familiarize yourself with these great LED's.
Cool Neon now also carries a wonderful developers shield to easily connect your TCL strand to an arduino or seeeduino, the few dollars are well spent if you want to save some soldering hassle and be able to disassemble your hardware with ease when you please. With your LED's now connected, install the library and run some of the example code provided to make sure your lights are working properly.
With our sensors and actuators now hard wired we have a completed circuit! Position your LED's in selected areas and tack them into place with hot glue or the adhesion method of choice, ideally one that will transmit or diffuse light in a beneficial way. Suspending your microcontroller in the center of the cube with your connecting wires is a good solution to prevent an unwanted shadow inside your cube.
Now we must combine relevant code for each side of the input/output equation to get the lighting animations we want. I'll provide some of my own example code (excuse the silly naming) made through mish-mashing and experimenting with various code from other helpful sources. You can scale it to as many sensors as you need and have pins for. With the code uploaded and working, continue tweaking variables such as your capsense totals, change_time[i] values (doing some math functions to your times here is GREAT for making complex animations), current_color[i] values and defining your own colors by combining rgb values is also extremely fun and useful to get whatever light best complements your piece and its environment. Experimenting here is hours and hours of fun.
After you have your code exactly where you want it, disconnect your arduino from your computer and attach your arduino power supply, make sure everything is still working the same. We now have a working and unique touch sensitive lamp! Let's conclude with some finishing touches that can be done depending on how you want to display your lamp.
Step 5: Finishing Touches
If your lamp is best suited for hanging, the final face must obviously be attached. Take this top face to your drill press and put a hole in each corner in order to run a wire through. Grab your wire cutters and snip your wall wart power supply in half, strip the wires on each side. Now grab your spool of copper wire and measure a length of wire to hang the lamp by, 8 feet was sufficient for my needs. Duplicate this length of wire so that you now have 4 wires total, one for each corner of the cube. Two of these wires will be your incognito power supply, the other two are simply support and symmetry. Connect two of these wires to where you power supply was, make note of which you use, and run all four wires through your top face.
Now join all 4 wires a reasonable distance from your cubes top, and start braiding. Braid all the way down to the end, where you will solder your live wires to your power supply. Now make sure everything is working as it was, and continue to solder your top face shut, you might just be done!!
Other aesthetic finishing touches can include brushing your solder with liquid copper sulfate after lightly cleaning your solder with steel wool. This clings to the solder giving it a nice copper finish. Different patinas are also a great way to bring a more aged and organic feel to your copper.
That's it! After all of this you should feel comfortable incorporating these techniques to make even more interesting objects, add new components or Xbees for wireless cube chatting, or whatever strange or useful idea you may find all of this information useful for creating.
Thank you so much for reading and if you have any questions feel free to email me directly at: