Galileo's Finger

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Hive13 Project
HIVE13 Tribute to Galileo
Status: Complete
Start Date: 3/27/2010


UPDATE: Galileo's Finger moved on June 2, 2020 and is now located near the entry door to greet visitors entering the Hive's new space at 2701 Spring Grove Avenue.

Galileo's Finger is an interactive, multi-media art-piece with a steam-punk theme. It is a tribute to Galileo Galilei, the father of modern physics. It resembles some form of a strange rocket ship blasting off from its base. It serves as a kiosk and physical representation to symbolically show all that is the concept and promise of the Hive13 Maker Space in Cincinnati, OHIO, USA.

It's construction exemplifies the variety of maker crafts practiced at the Hive; glass blowing, wood working, metal fabrication, laser cutting/engraving, 3-D printing, microprocessor applications, custom PCB design, electronic soldering, software programming, and dumpster diving.

It operates like a honey pot, intending to attract curious visitors to come together, combine their talents, and give back to the community in new and creative ways.

It starts with the symbology of the TRIAD of three primary colors, RED, GREEN, and BLUE. It is electrically-operated and always-on. It features three electronic sonar distance sensors (R, G, & B). These sonar inputs invisibly look out into the distance. The microprocessor uses these three inputs to operates a tower of 48 tri-color LED outputs. As people approach, the 144 controlled points of light become additional multiples of reflected light via a core infinity mirror within its body. People are attracted to come from the darkness into the light to make things interesting.

As a first person approaches from a first direction (say RED) the microprocessor responds with each programming loop to light an increasing number of red LEDs on a scale from 0 to 8. More RED is good, but by itself, is not enough.

When a second and third person are also drawn in from their own unique direction, things start to get interesting. The quantity of RED, GREEN, and BLUE LEDs illuminated in each programming loop increases and decreases as different people representing different talents come-and-go, not quite reaching the potential of their union.

The symbology of three points coming together to form a strong triangle is achieved when all three sonar inputs reach their maximum value and all LEDs are illuminated in the programming loop. The program branches in a new direction to celebrate the potential of the resulting SYNERGY. The progression of RED, GREEN, and BLUE lights counts down into the core. There the three colors circle faster and faster, ultimately combining into a single white light. This white light from the core then reverses direction, radiating out all of the colors of the rainbow back into the community. This lasts for a while and then resets. It waits to see if the combination of needed inputs is still around to do it again and again. What is your primary color and what is your contribution to the rainbow? Come to the Hive and find out!

So that's all pretty weird and deep thinking, but what is the connection to the man Galileo and his finger? Read on my friend...

The project started back in March 2010 when Hive friend Warren Trefz and Cincinnati's River City Works group decided to gift the Hive with one of their one-of-a-kind works of custom blown glass. Warren is the instructor and project director at this unique glass blowing facility in Cincinnati.

Warren's gift was essentially an egg-shaped glass goblet with a glass lid containing a glass replica of Galileo's finger. It turns out the remains of the real man Galileo's real finger is contained in a similar goblet in a science museum in Italy. Why? Well, Galileo's invention of the glass telescope in the early 1600's was beginning to provide hard scientific proof for the Copernicus theory (that the earth revolved around the sun and not vice-versa) in a time when the powers to-be in Italy (the Catholic church) did not approve of such heresy. The whole thing makes a very interesting story that needed to be told.

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The Museo Galileo in Florence, its presentation, and a close-up of Galileo's real finger.

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Our goblet and its lid, how they fit, and how we assembled them.

So in the glass piece Warren and the River City Works folks made for us, the finger kinda looks like a glass pickle, the lid is not attached to the goblet, and the piece needed a bit of finishing before it could be safely displayed. HIVE member Jim took on the task of making an appropriate presentation for this unique artifact. The result has been an evolving/expanding active project that exhibits some of the HIVE's woodworking, brass forming, laser etching, dumpster diving, and Arduino-based electronics skills.

The above photo shows the egg-shaped, blown-glass goblet containing the green glass finger. There is a mounting that holds the glass lid onto the top of the glass goblet. The effect resembles a vintage hot-air balloon. The implications of lots of hot air are entirely appropriate. The goblet/balloon sits on top of a SteamPunk rocketship. The cockpit is half of a scavanged hall chandelier having a six-sided brass frame and beveled glass panel inserts. Re-purposing this chandelier is an example of the important maker skill of dumpster diving.

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The hex-shaped wood body is stained and varnished mahogany and the six feet resemble rocket nozzles like the whole thing is launching off. Laser etched panels on the sides explain the Galileo story in the original Latin and with an English translation. The third image is a top down view looking inside the body to show the location of the power supply.

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Above is friend-of-the-HIVE Clyde Kober and his Epilog laser. He is showing the laser etching he did on one of the three sign plates for this project. Our contact with Clyde's laser-etching services was our first exposure to DIY laser work. Check out his company website at the following link. The Hive ended up buying one of Clyde's used lasers and quickly upgrading to a second larger laser as well. Thanks, Clyde. They look great!


Above is what one of the signs looks like mounted on the body. Click on the photo for a close-up. It was spray-painted black and then the paint was sanded off flush with the top surface. The black paint stays in the laser-etched cavities of the border and lettering and has a really sharp look.

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Click on any of the three above figures to see the artwork for the three signs; in the original Latin, the English translation, and the background for the story.

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We decided this bizarre thingie needed to sit on something to be appreciated; but just any old table would not do.

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We made a custom hex-shaped wooden base that makes the connection to the launching point at Hive13 in Cincinnati, Ohio, USA. The above photos show just this base. We inserted a 36" round glass table top (more dumpster diving) between the base and the rocket ship goblet/obolosk/thingie that sits on the glass table top and the base structure.


The custom base and glass table top ended up much nicer than the generic table we would have used shown in the background of this photo. Everything is just great, except... this unique obolisk/kiosk thingie can't just sit there, it has to do something. Enter the Arduino LED add-in to the project. The idea is for it to have some autonomous interactive function that would attract the attention of the casual passer-by.


The above picture shows the hex-shaped structure and the original six approach vectors (reduced to three) radiating out from where the three distance sensors would be located. We wanted some distance sensing ability when a person approaches from one of the three directions. The desired range is roughly 72" down to 6", more or less. These are analog inputs to the Arduino. The Arduino uses these inputs to illuminate various combinations of red/green/blue LED light as outputs. A closer distance would illuminate more LEDs of each color. Once up close, you could wave your hands in front of the sensors to dynamically change the RGB combination of merged LED light.

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The left image above is the prototype using an Arduino hooked up to a MaxSonar EZ1 ultrasonic range finder as an input to pulse a set of six red, green, and blue LEDs. The pulse rate increases as you approach the unit. It was only a prototype, but showed promise and was exciting to see live. The right image is a second prototype using a Boarduino (Arduino clone) to drive three TLC5940 chips and 18 tri-color LEDs. The animation sequence starts with LED1 switching from red, to green, then blue, then the same at LED2, LED3, etc. up to 18 and back down again.


Above is a poor resolution image of the original schematic for the first design. There is a more complicated arrangement with three sets of 6 LEDs. The original implementation used three AD5206 digital pots (each with six channels) per the Arduino example

Well, the AD5206 digital pot chip turned out to be a bad choice, or a 'dry hole' as a well digger would say. Several HIVE yodas (thanks IanD and JamesS) have pointed out that changing voltage on LEDs is a poor way to control their brightness. They said PWM (Pulse Width Modulation) is the better way to go. While the Arduino itself has a few PWM capable outputs, it does not have nearly enough for what we want to do here. However, in the magic world of Integrated Circuits there seems to always be some other way. That turned out to be SIP communication to a chip that can do what you want to do. Enter the Texas Instruments TLC5940 16-channel LED driver chip with DOT correction and grayscale PWM control. There is an Arduino playground example on the web at The chip was only $3.50 retail at Digikey or Mouser and TI will even send you a limited number of free samples if you only ask. The following links are for the Texas Instruments TLC5940 chip as the LED driver.

For smaller size reasons we chose to use the PWP form factor over the NT (DIP) form factor for this chip. The bottom of the PWP form factor chip serves as a thermal pad requiring it to be surface-mount soldered. This was another advantage as it forced us to get practice with our hot plate surface mount soldering techniques described later.

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The first photo above shows the rescued ATX power supply that will provides a regulated 5.0 VDC at 10.0 amps for the arduino with sufficient current to drive all 144 LEDs. It is mounted in the wooden base. The green 'enable' wire makes an on/off switch. The second photo shows the mounting for the three MaxBotix MaxSonar(R)-EZ1 sonar range finders. The third photo shows CAD cross-sections for a multi-part stack of acrylic disks with cutouts configured to mount the top six LEDs. These cross-sections show five different acrylic disks (at .093" and .220" thick) with cutouts that position the LEDs and connectors. Galileo.LED.plate.bottom.jpg Galileo.LED.plate.side.jpg

The photos above show the laser-cut acrylic stack for the pancake that holds the top six LEDs. It turned out really nice.

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The 3-D image on the left above is a partial view of just the lower LED and brass rod structure. Only one of the six wings is populated with rows of brass rods and LEDs. The eighth (top) level of LEDs is built inside the core stack at the top as can be seen in the following cross-section. The center image above shows top and side views of the new design for the inner core. This structure has 48 tri-color LEDs arranged in rings of six on eight vertical levels. Each LED location is typically powered to be individually red, green, or blue, yielding 144 primary color addressable locations. Note all three (RGB) inputs can be simultaneously powered to yield a rainbow of color choices at each LED location. The core structure exists to route all the wire leads from where they are on the PCBs to where they need to be for the LEDs. Below the core is a matrix structure of brass rods that brings power out to each LED. Four rods are needed for each LED; one lead is the common/shared (+) anode and the three leads are the color cathodes (red, green, blue). The view on the right shows the detail for the cut out pattern for each unique acrylic layer in the core stack.

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The above views show the cross-section of the core structure and two different 3-D views of the bottom LED structure. The core exists to route the 48 red, 48 green, and 48 blue wires from the six side-mounted custom LED Driver PCBs, to the structure of brass rods and ultimately the 48 LEDs. The core structure is a multi-layer stack of about 42 individual acrylic layers. Each layer is different, typically dedicated to routing six wires for one level and one LED color.

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The above three views show the design of the top core stack of acrylic layers. The Lilypad Arduino mounted onto the acrylic layer that is colored purple. The base of the goblet sits on top of the tan layer and is constrained by the top blue layer. The two cross sections are cut 30 degrees apart to show the different internal features that include the tie rod hex nut pockets and sensor ribbon cable passages.

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The above views show separating and preparing the numerous laser cut parts, and the setup at the start of the assembly. The anodes (+) for each LED are common and can be ganged together. The third photo shows how the eight brass rods from each of the six wings, are gang soldered and a jumper wire from each gang is then soldered to a brass disk washer installed on the central all-thread. This simplifies the first 25% of the detail wiring.

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All the brass rods are inserted into the structure, then the appropriate red, green, or blue hookup wire lead is soldered onto the top of each brass rods. The hookup wire is organized for the addition of each layer in the core stack.

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These views show the 48 red, 48 green, and 48 blue wire runs as each layer was added, threaded, and assembled in the core stack, one-by-one.

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These views show the core. Galileo.lilypad.JPG

These views show the top of the core and the I/O wiring to the Lilypad Arduino. The Arduino is hidden under the base of the goblet when it is all assembled.

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These views show the assembly and the mirror effect.

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The above sketch is hard to see, but it shows the wiring of the Arduino LilyPad and the PCBs. The other two views show the LilyPad from AdaFruit and the custom circuit boards built for this project. The core needs six boards, but we made nine to have some spares to practice on. Two of the custom boards in the above picture have been populated with seven remaining to do.

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The above images are from EagleCAD. They show the wiring schematic, the board layout, and the "cream layer" that was used to make a solder mask stencil to reflow-solder the surface mount components for the boards.

Use this link for a detailed description of the reflow-solder operation on the PCBs.

OK, so the whole thing finally turned into a finished project. It has continued to operate year-after-year in the time since. There is a lingering problem with the second blue circuit board to fix. But that is typical for Hive projects. There is always work to be done.