If you're anything like me, you probably have a zillion projects all over the house, driving your spouse/girlfriend/monkey handler crazy. If so, I highly recommend using your geeky skills to make something nice for them every once in a while. The reasons being: it's a nice thing to do; it shows that your weird hobbies can have benefits for them too and not just make a mess of the house; and, it gets them off your back for a little while you try to get a workshop space set up elsewhere.
So, with that in mind, I'm going to show you how to use your electronics skills to make an incredibly cool and romantical Valentine's Day gift for your sweetie. It's inexpensive, looks great, and will make a great impression on your girlfriend/boyfriend/wife/husband.
Step 1: Supplies
An old glossy magazine
Graphics software (I used Adobe Illustrator)
6" x 6" copper clad board (single sided)
Extra fine sand paper - 220 grit
Clean lint-free cloth or rag (like an old cotton t-shirt)
8.5" x 11" sheet of plain bond paper
Ferric chloride etching fluid (mixed from powder form)
Glass jar (to mix and store the etching fluid)
A decent weight plastic bag, like a zip-lock bag
A wooden chopstick or other disposable stick (to stir the etching fluid)
9" x 9" or larger pyrex baking dish
Dish scrubbing sponge
Fine point artist's paint brush
A tube of artist's acrylic paint (any color)
Rotary tool and tiny PCB drill bits
(10) Red LEDs
(1) 10-Position connector/right angle cable mount
(1) 10-conductor ribbon cable, about 5" long
(2) Male header pins - 5 pins each (cut long strip of pins in half)
Soldering iron and flux-core solder
Diagonal wire cutters
Clear spray acrylic or enamel (gloss or semi-gloss)
Arduino controller (I used the super-tiny RBBB kit from moderndevice.com)
Step 2: Create the Art
I started with this illustration at Vector4Free.com, then copied, pasted, and rotated parts to make a heart shape and fill in around the open spaces.
Once I was happy with the artwork, I outlined it with a white outline and put it on a black background. The reason for this is so that we're not etching large areas - remember, anything that's BLACK will be masked and stay as copper on the final board. The etching fluid loses its effectiveness if you're dissolving large amounts of copper, and besides, the copper is the best-looking part of the board, so we should keep as much of it as possible.
The artwork sits inside a border, separated from the circuit (outer) portion of the board. I considered integrating the LEDs with the actual heart, but I didn't want to draw the ways for each LED and mess up the flowy artwork. Also, I really like the contrast of the curvy art with the straight lines of the circuit all around it.
I've included my final artwork (in both Illustrator PDF and a 1-bit TIF file) for you to use. There is a big open area across the top - feel free to add customized text, or maybe a secret message in Binary for fun (Use an online ASCII to Binary converter)
Step 3: Mask the Board
Cut your glossy magazine cover down to 8.5" x 11" and load into your laser printer. I had a few paper jams and ended up using 4 sheets before I got a usable print, so you might want to get a few backup sheets ready. Use the manual feed and a straight paper path to avoid jamming issues.
TIP: Try to use light-colored covers so you can actually SEE your print once it comes out.
Print your circuit artwork on the magazine paper with your laser printer set to its darkest setting - you want as much toner as possible on your print. Remember to print a mirror image - the transfer process will revert it to right-reading! Trim the print down to fit on your copper board. Cut the printed artwork down to the size of your board (6" x 6" in this case) so you can use the overall size of the paper to center the print on the copper.
Give your copper board a good once-over with the fine sandpaper to rough up the surface and help the toner mask adhesion. Once the board is sanded, wipe it down with alcohol and a clean, lint-free cloth and handle it by the edges only.
Center your glossy paper print on the board, toner side down, then place the sheet of plain paper over it to protect your iron. Get your clothes iron nice and hot (linen setting - no steam!) and iron over the paper. Do this on a hard, flat surface like a granite countertop or a piece of MDF board on a sturdy table. Don't do this on plastic-type countertops without a board, or you might melt the counter! Press hard for about 15 seconds, then lift and move to another section, and repeat. Make sure you cover the entire print like this. What you're doing here is melting the toner (which is actually a finely-ground plastic) and fusing it to the copper surface.
Fill your pyrex dish with hot tap water and soak the board (which now has the magazine paper print stuck to it) for 10 minutes or so. This should soften the paper enough to let you peel it off with your fingers. If it doesn't all come off, soak it again for a few more minutes. Rub the last bits of paper off of the toner. You should end up with a copper board with your toner clearly visible on it.
Chances are that your mask didn't turn out perfectly, and you might have missed a few areas with the iron. Go ahead and paint in those areas with the acrylic paint, paying extra attention to the areas around the traces and where the components and LEDs will go to make sure you don't have any shorts. If you need to paint in fine details that are too difficult to do with your brush, just put down a rough blob and then scrape away parts of the paint with an X-Acto knife. I used red paint so the painted parts would contrast with the toner, but you can use whatever color you have.
If your toner has lots of dropped-out areas, you might want to start over rather than try to paint in the problem areas. If this is the case, use the dish scrubber and running water to remove the toner, then clean the copper with alcohol and try ironing on another toner mask. I had to do 3 before I was satisfied with the results.
Once your paint is dry and you are happy with your toner/paint mask, it's time to get to etching!
Step 4: Etch the Board
PLEASE FOLLOW DIRECTIONS AND WARNINGS WITH THE FERRIC CHLORIDE ETCHING FLUID. It's nasty, caustic stuff, and will stain anything it comes into contact with.
Alright, goggles and gloves on? Good! SLOWLY mix the powder into a glass mason jar full of water (follow instructions for amount of water to use). Use care and go slowly - it gets HOT and may spatter if you add it too fast. Mix it up with a chopstick or other disposable wooden implement, then throw your mixing stick away immediately - don't put it on the counter or table, or you will stain them.
Put your masked copper board face up into the pyrex baking dish, then slowly pour the etching fluid in, taking care not to splash. Let it sit for a few minutes, then carefully agitate the dish to mix the fluid around. Just tilt the dish a tiny bit. Do that every few minutes until you start to see the greenish or tan-colored board under the copper, probably 10 minutes or so.
When it's done etching away the exposed copper, remove the board and rinse well under running tap water.
Step 5: Clean Up the Board
Use the abrasive side of a dish sponge to scrub off the toner and acrylic paint under running water. Get the copper nice and shiny! The sponge should be abrasive enough to remove the toner, but not enough to scrape off the copper, so scrub away.
Dry off the board and keep handling it by the edges to keep it from tarnishing. Looks great, doesn't it?
All done with the etching fluid? CAREFULLY pour it back into the glass jar. If your jar has a metal lid, put a piece of plastic bag over the opening of the jar before screwing the lid on, or the Ferric Chloride will corrode the metal lid.
Step 6: Drill Holes for the Components
Use the rotary tool and the tiny bits to drill holes for the LEDs and connectors. Keep the rotary tool vertical and stable so you don't break the bit. It's nearly impossible to do it by hand and not break bits though, so be sure to have extras on hand.
Eye protection is essential here - the first drill bit I broke flew off and hit the lens of my glasses!
TIP: If you're going to be drilling a lot of holes in circuit boards, I recommend getting a mini drill press type stand for your rotary tool. They run about $35-40 and are pretty handy for mini routing projects or drilling, and will save you from the headache of broken drill bits.
Step 7: Solder the Electrical Components and Plug in Arduino
Solder in the LEDs. I wanted the LEDs on the back side to give the lighting a more subdued effect, but you can put yours on the front if you want. Make sure the cathode (negative, or shorter lead) is on the Ground side. Just remember that the long trace gets the positive (longer lead) side of the LED.
Solder in the two 5-pin headers, making sure the long (pin) sides are facing towards the back. Once installed, the spacing for the pins on the back should match the 10-position cable connector, so you can just plug it in. Install the 10-strand ribbon cable into the connector. The other end of the wires will plug into the Arduino's digital pin outs, #2 through #11. Split and strip about 0.25" off of each strand. Solder in a single wire for the Ground (shown as a green wire in the photo). This will attach it to the Arduino's Ground pin. Make sure it's long enough!
After your soldering is done, snip off the ends of your LEDs. Give the copper one last cleaning to remove any dirt or skin oil, then spray it with a couple light, protective coatings of clear varnish to keep the copper bright and shiny.
You can attach your Arduino to the back of the circuit board with a couple small pieces of double-sided foam tape.
Step 8: Upload the Arduino Sketch to the Board
If you need help, see the excellent tutorials on the Arduino over at LadyAda.
Step 9: Mount the Board for Display
To make space behind the circuit board for the RBBB (Arduino clone) and the header pins, I hot glued pieces of synthetic cork to the back of the board. Small wood screws hold the cork pieces to the backing board of the frame. A small hole in the backing board allows the DC power cord to plug into the Arduino
I considered mounting the Arduino in a visible place below the board, but decided against it. I like the clean look of the board in the frame, with the black background. I realize the LEDs won't have as great an effect against the black background, but it's going to be off more often than it will be on, so I want to make sure it looks good when off.
Step 10: Improvements and Next Steps
1) Using SMD components would allow the LEDs to be on the front of the board, and would look totally hot. I was in a hurry to finish this project in time for Valentine's Day, and so I went with through-hole components rather than try to learn to work with SMD parts.
2) The RBBB (Arduino clone) is small enough that it could be integrated with and soldered directly onto the circuit board itself. I had considered this from the beginning, but I only had an Arduino Duemilenove at the time, so I went with the connector setup shown here.
3) I would like to add an ultrasonic distance sensor so that the lights come on whenever someone approaches the piece, though it would have to be outside of the frame somewhere (won't work if it's behind the glass!), and I'm not sure I want to mess with the aesthetics of the piece by adding the sensors to it. Perhaps an infrared proximity sensor would be better.
4) The toner mask method is a complete pain the arse, but it is cheap and accessible, and gives great results (when it works!). I will probably use a different masking method next time.