Dossier #2 from the Graffiti Research Lab: the Electro-Graf. An electro-graf is a graffiti piece or throw-up that uses conductive spray-paint and magnet paint to embed movable LED display electronics. The following pages describe the materials and processes used to create the prototype indoor and outdoor interactive electro-grafs created in the lab at Eyebeam.
Check out the Graffiti Research Lab site and watch the DIY Electro-Graf Vid or the G.R.L. flickr group for more on the elctro-graf.
Step 1: Materials/Parts List
The basic materials for building an electro-graf can be purchased using a combination of online vendors and local hardware stores. A small (100 LED, 4' x 4 ') electro-graf could run ~$100. A large piece could cost as much as $2000 dollars, but thats just a WAG.
Part: Super Shield conductive spray-paint
Vendor: Less EMF
Average cost: $22 per can
Notes: this is the secret weapon.
Part: spray-paint, color your choice
Vendor: I use Krylon from the local hardware store
Average cost: $22.50 for 6 cans
Notes: use what you like.
Part: Magnet paint
Vendor(s): Less EMF for premixed indoor paint called Magic Wall or Magically Magnetic, Inc. for paint additive. This additive can be mixed with indoor or outdoor primer sealer.
Average cost: Magic Wall @ $29.95/quart; Magnet paint additive @ $15/quart and primer sealer @ $8.50/quart
Notes: I used Zinnser BULLS-EYE primer 1-2-3 primer sealer for the base paint on the outdoor electro-graf proto. It's the good stuff. Your local hardware store is sure to have a thick outdoor primer that will work. You can get worse paint for less money. Note: Don't believe the hype. The paint itself is not magnetic. It is just metallic and magnets adhere to it.
Part: 10mm LEDs. The color choice is yours.
Vendor: Again, it's my crew Denny, Ann, et al. @ HB Electronic Components.
Avg. Cost: $0.20 per LED
Notes: you can use smaller LEDs, but it's just not my taste.
Part: 1/8" Dia. x 1/16" Thick NdFeB Disc Magnet, Ni-Cu-Ni plated
Vendor: Amazing Magnets
Cost: $9.00 per 100 magnets
Notes: Cost reductions for larger quantities
Part: Power supply.
This will vary based on number and types of LEDs, circuit design and environment. You must supply the LEDs with >= 3 volts DC power. Depending primarily on the number of LEDs, you can use anything from a $2 9 Volt to a $50 dollar car battery to a regulated 500 Watt power supply if the proper current limiting components are used. In the lab I use a regulated DC power supply. We will discuss this more in the following steps.
Vendor: your local hardware store should have painter's tape and masking tape. Get both.
Cost: $2-$5/ per 60 yard roll
Notes: 3M painter's tape is blue and has less adhesion than masking tape. Both tapes are useful in different situations.
Parts: 5 minute epoxy
Vendor: your local hardware store should have 5 minute epoxy
Cost: $5 dollars for one tube
Notes: This is some delightful shit. Get the kind in the two part dispenser.
Part: Stencil materials -- Acetate, Manila Folders.
Vendor: Your local art store or office store should have acetate, cardboard and file folders.
Avg. Cost: $10 for a 25' x 12 ft. roll of acetate, folders and cardboard vary in price and is often found for free.
Part: Stranded wire
Cost: $3 per roll
Notes: any 18-24 AWG stranded hook-up wire will work. Solid core wire is too brittle.
Part: 1/4 or 1/2 Watt resistors, the choice of value is yours
Avg. Cost: $1 for 100 pieces
Part: 3/4" Foil Tape
Vendor: Newark In One
Avg. Cost: $18 per roll
Part: Conductive Epoxy
Vendor: Newark In One
Notes: The epoxy is optional. It is used to attach magnets to electronic components and wire.
Part: you can add electronic components to create LED sequences, animation, solar power, etc. You may need stranded wire for connecting your LED traces to various power sources.
a respirator, a mutimeter, paint brushes, containers for mixing paints, exacto blades, clay
Step 2: Design Your Piece
I won't get into any depth regarding designing stencils or graffiti pieces. I will also not go into detail on designing circuits for driving and sequencing LEDs. I will direct you to online and print resources where this information can be gleaned from reputable sources. I will also explain the specific design we implemented with the first two prototype electro-grafs.
Links to stencil design examples and tutorials:
Links for basic electronics for non-experts:
Tom Igoe's Physical computing online resources
Physical computing in print by O'Sullivan and Igoe.
The first prototype electro-graf, executed in the lab at Eyebeam is a mash-up of images of the state-of-the-art in military robots combined with quotes from soldiers, officers and military bloggers. Marine General, James Mattis, said," It's fun to shoot some people," when discussing his service in Afghanistan where US forces have killed over 3500 civilians. That's a lot of fun. More fun that even Bin Laden had on September 11th I bet. The image in this design was taken from promotional material about Foster-Miller's robot TALON. The weaponized configuration is called SWORDS. SWORDS was developed, in part, in a suburb in New Jersey at a place called Picatinny Arsenal.
"The TALON robot is the only mobile platform currently certified by the Department of Defense for remotely controlled live firing of lethal weapons." Read: the first robot licensed to kill.
For this piece we used a Stencil Revolution tutorial to create the stencil in Illustrator CS1 and cut them on a laser cutter. The control electronics were designed, built and programmed by Twin A in collaboration with a very good and up<a/> LED and video artist named <a href="http://www.villareal.net/">Leo Villareal. It is currently on loan from A for our experiments in the lab.
The first prototype outdoor electro-graf is currently up on the facade of Eyebeam. The design was intended to be minimal and entirely functional: to test the electro-graf capabilities in terms of size, weather-proofing, theft patterns, and public feedback.
Both electro-grafs are just technology demonstrations. I do not claim to be a writer, a bomber or an artist. I am a graffiti engineer. My intention is to develop and demonstrate tools that enable parity between the establishment and the graffiti writer w/r/t the ability to garner and direct attention.
Step 3: Apply Magnetic Coat
After you have chosen a location and time to execute your piece, you need to apply the magnet paint. If you are using the Magic Wall paint indoors, you can just apply the paint with a brush or roller. You need to paint on 2-4 coats for a reliable, robust magnetic attraction.
If you are using the paint additive and a primer sealer, you need to mix the powder additive to thick, primer/sealer paint. Follow the instructions on this site to properly make the magnetic paint. Add 1 cup of additive per quart of paint. Remember to follow the instructions on the paint can regarding the appropriate temperature for applying the paint .
Step 4: Apply Conductive Coat
Now, apply the stencil circuit using Super Shield conductive spray-paint. You will need to apply 2-5 coats of spray-paint for best functionality. Use the multimeter to test for conductivity and resistance. The trace resistance should be less than 10 -20 Ohms per foot. To decrease the resistance, add more coats of paint.
Make sure you functionally test the circuit whenever you can.
Step 5: Tape Contact Pads
If you intend to add a topcoat to the electro-graf, like in the case of the prototype indoor electro-graf, you need to put masking tape on the circuit stencil to create contact pads. These are where the LED leads or the wires will make contact with spray-on conductive traces and close the circuit. I used 1/2" by 1/4" pieces of masking tape to make the contact pads. Remember to put these on before you spray your topcoat!
The outdoor electro-graf did not require a topcoat of paint or tape to cover the contact pads.
Step 6: Apply Topcoat
Once you have taped the contact pads, you can apply the topcoat. I used Krylon green fluorescent and black ultra-flat spray-paint. You can get specialty caps at a number of online stores. Here is one. Fat caps help reduce the time it takes to cover large areas with a single color. Remember to allow sufficient time for the paint to dry between coats.
Note: acetate produces a tight stencil with less under-spray than cardboard or thick paper. But acetate is flimsy and requires much more taping to stay flush with the wall.
Step 7: Remove Tape
Now, you can use an exacto blade, tweezer or small screwdriver to remove the tape over the contact areas. Once the tape is removed, use the multimeter to test the traces conductivity and resistance. Remember to functionally test the circuit every chance you get. and pay attention.
Step 8: Make Mods to Electronics
Every electronic component needs to interface with the wall in two ways: electrically and mechanically.
Components like wire, LEDs and circuit boards can be taped, epoxied or screwed into the wall. Another option is to create a metallic surface on the wall (using magnet paint) and then modify the electronic components by adding rare-earth magnets. The magnet mod-ed components then adhere to the section of the wall where the magnet paint has been applied. Wire can be attached directly to magnets using conductive epoxy. Be patient with conductive epoxy and don't speed-up the curing process with heat. Attaching magnets to LEDs is a bit more difficult.
Attaching magnets to LEDs
I have developed a simple technique for attaching magnets to LEDs using old, used exacto knives. First, I created a LED holder on the laser cutter. You can also use a little mound of clay, putty or, I suppose, chewing gum. While holding the LED with its leads pointed up, mix a small batch of epoxy. Place the magnet on the end of a used exacto blade, about 1/4-inch from the tip (see picture). It will adhere magnetically. Put a dot of epoxy on the magnet and on the LED. Now, with the magnet facing down, let the tip of the blade slide between the leads of the led until the magnet is laying face down on the underside of the LED. You can adjust the distance between LED leads and the magnet by moving the magnet further away from the tip of the blade. THE MAGNET SHOULD NOT TOUCH THE LED LEADS. This will create a short since the magnet is conductive. Once one has dried you can repeat the process with a second magnet on the opposite side of the leads. The first magnet will help keep the blade in place for the second magnet. Confused?? Just check out the flicks and give it a try.
You can connect wires and LEDs to the wall to make electrical connections in many of the same ways. To attach wire to the wall just bond the twisted strand of wire to a magnet using conductive epoxy. Then connect the magnet to a wall that has both magnet and conductive paint applied. The circuit will connect across the conductive magnet. To modify LED to make an electrical connection you can simply bend the LED leads so that they run parallel with the underside of the LED. When the magnet mod-ed LED is adhered to the wall, the bent leads are pre-loaded via magnetic attraction onto the conductive traces. This way you can remove and re-configure the LEDs on the wall at a number of locations by design. Look at the flicks for more details on the process.
Step 9: Integrate
Now you can put the LEDs on the wall, connect the power supply and any control electronics and turn it on. Depending on your design this could take a second or hours. If you use the techniques described, your LEDs can be reconfigured along the piece (as in the case of the outdoor electro-graf) or LEDs can be replaced and colors changed (as in the case of the indoor electro-graf stencil).
In some cases you will need to add a resistor directly to the LED cahthode lead. This will help prevent the LED from drawing too much current and getting damage and reduce the voltage drop that occurs in a parallel circuit due to LEDs that are not current limited. To determine you resistor value use the following easy formula.
(SupplyVoltage - LEDForwardVoltage)/ NominalLEDCurrent = ResitorValue
In the case of the outdoor electro-graf we used the following values:
(12 VDC - 3VDC)/.020 mA = 450 Ohm resistor
The main design driver for the magnetic paint and magnet mod-ed electronics was ease of integration. This step should be relatively easy.
Step 10: Applications and Upgrades
The materials and proccesses discussed in this section will work on concrete, brick, cardboard, paper and plastic. The cost and complexity of an electro-graf can vary wildly. You can construct an electro-graf that requires days of work and interfaces with complex eletronic circuitry or even a networked back-end architecture or you can make an electro-graf throwie with copper tape and a few LEDs that can be up in five minutes.
G.R.L. agents are working right now to improve and innovate upon aspects of the electro-graf, including:
the prevention of rust, the integration of sustainable power sources, the interaction design and more interactivity. If you want to become a G.R.L. agent or are just interested in getting more involved, contact [mailto:firstname.lastname@example.org resistor]. Good luck and get em up.
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