Wedding LED Unity Display

I’m getting married in less than a week from now. My fiance and I didn’t want to use a traditional unity candle for our ceremony, so I came up with something a little different. I used some RGB LED strips to create my own LED unity display.

 

The LEDs are controlled by a relay and two arcade buttons wired in series. When both arcade buttons are pushed the LEDs in the two smaller frames are are turned off and the LEDs in the large frame are turned on.

 

Completing this project required using the laser cutter, the CNC router, making my own PCB, and even a little bit of wood working to put the frames together.

 

 

 

 

A Simple Aux Input For iPod Speaker Systems

The first generation of Bose SoundDocks did not feature an aux input jack, they are only compatible with the 30 pin connector of iPods and iPhones.  Lately, my music player of choice is my Droid Razr, which has 60+ Gb of music on it, even more in the cloud, and no 30 pin connector.  I decided to add an auxiliary input to my SoundDock in the easiest and quickest way possible. I made an adapter cable using half of a $6 iPod extension cable, half of a $1 3.5mm headphone cable, and two necessary resistors.  I can plug this adapter cable directly into any unmodified SoundDock, or any other amplified speaker system that has a 30 pin connector.

It turns out that the SoundDock is smart, and will only power on when it senses 3.3VDC on pin 18 of its input connector.  Luckily, it also outputs 12VDC on pin 19 to recharge the attached iPod’s battery.  To trick the SoundDock into turning on with no iPod attached, I made a voltage divider by soldering a 20 Kohm resistor between the wires connected to pins 18 and 19, and a 4.7 Kohm resistor between the wires connected to pins 18 and 1.  The voltage between pins 18 and 1 was measured to be ~3VDC, which isn’t 3.3VDC, but is sufficient to power up the SoundDock.  I soldered the three pins of the 3.5mm headphone jack to the 30 pin connector’s wires as follows: Ground to pin 1, right audio to pin 3 and left audio to pin 4.  I used 1206 surface mount resistors because they measure only 3.2mm by 1.6mm, a size which fits conveniently under the shrink wrap joining the two cables.  The most time consuming part of this two hour project was identifying which color wires were connected to pins 1,3,4,18 & 19, and determining if the pin on the left of the photo was #1 or #30.

Makers, assemble!

Yeah.  Having access to a laser cutter is pretty boss.  I’m planning to wear this to the premiere of a certain movie this weekend.  Four layers of acrylic; two diffuse, two opaque.  11 LEDs, 11 100 Ohm resistors, some phone cord, some solder, and a 9V battery.  There’s no lack of great pages on Instructables about how to make your own.

PCB with Lasered Paint Resist and Fast Sponge Etching

TomG shows how he etches PCB boards using paint, a 25W laser cutter, Muratic Acid, 30% H2O2 and a sponge. Much frothing ensues.

The technique is a neat one, given the presence of a laser cutter, because it can take you from copper clad to etched board in a pretty quick amount of time.

One note, the Muratic Acid is actually from a pool supply store, not Home Depot. It is, of course, dangerous. Wear safety goggles, use gloves, use in a well ventilated area. (The acid smells like a punch to the nose, don’t inhale it)

The Critic

This is “The Critic.” It’s the USB accessory version of a red pen: Once armed by rotating the red safety cover up, the device is activated by simply flipping the toggle switch.  When connected to a computer via the convenient USB plug, it will begin to delete text, continually deleting until all the (presumably erroneous) text preceding the curser has vanished. At that point, the safety cover can be lowered, thereby deactivating the device.  The Critic is an indispensable tool for use when the document you’re editing is just so full of errors that your fingers begin to ache from holding down the delete key.  The Critic measures 3″ by 2″ by 2″ tall, and was designed to fit conveniently within arm’s reach, beside your keyboard or mouse.

I was inspired by the open source work of Pete at RasterWeb! and his recent effort to bring “The Button” to a wider audience of busy or non-makers.  He has freely helped tens of people create their own buttons, but is now able to fulfill requests for preassembled units. Among other applications, these USB buttons can be used as the shutter control of  Mac powered Photo booths at public events. These photo booths are powered by Sparkbooth, which can automatically upload the photos to Facebook, Twitter, tumblr or other social media sites.  His buttons emulate a keyboard, and contain an Arduino Teensy (only 0.7″ by 1.2″), which is a USB based AVR microcontroller.  Despite the Teensy cost of $16, I saw an opportunity for cost savings by opening a standard USB keyboard and spending a few minutes to extract and reverse engineer their compact circuit board.  Although this isn’t a solution suitable for even small scale production, it can work for a one-off prototype, like The Critic.

Below are several photos that show the process of opening the keyboard to extract and modify the circuit board.  When the top of the keyboard is removed, a sheet of silicone ‘popples’ is revealed.  These ‘popples’ are the springs under each of the keys.  Under this layer are two sheets of thin plastic, one with conductive ink traces that are (mostly) horizontal, and one with conductive ink traces that are (mostly) vertical.  These layers of traces are separated by a small gap.  When a key is pressed, a protrusion on the bottom of that key’s popple pushes the two layers of plastic together at this location: connecting one of the vertical traces to one of the horizontal traces. These traces are routed to the circuit board via a row of contacts under the front edge:

   

The chip (under the black epoxy potting on the bottom of the board) detects this electrical connection, and outputs the appropriate character over the USB cable.  The keyboard, popples and plastic layers can all be replaced by an external switch and wires soldered directly to the circuit board.  The photo below shows wires (whose free end is to be connected to the switch) soldered to the pads required to output a space bar character.  To output other characters, simply follow the vertical and horizontal traces to the board, and solder wires to those pads instead.

    

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My neverending quest for quick turnaround prototype PCBs

For years I have dreamed of a fast way to prototype PCB for projects I am designing.

20 years ago I was using rub on drafting tape and stencils – slow and spotty results.

I tried to modify a plotter to plot resist directly to a PCB – no luck.

Magic markers – I’m no artist.

5 years ago I hacked a laminate router by tapping into the stepper controllers and adding a better Z axis – It can rout boards ok, but takes some tweaking.  It only does fairly wide traces.  But its great at drilling holes!

2 years ago I tried the inkjet printing systems – lots of smeared wet ink and poor registration, not very effective.

I opened up a laser printer and tried to get a board to go through it – almost worked, but the fuser was to narrow to take the board.

Although I haven’t found a fast system yet, I get by with the PNP Blue material and a good laminator.  Although I am regularly disappointed when dust, not quite clean boards, minor wrinkles and other issues leave gaps in traces that need touching up.

Which brings us to the latest attempt:

Now that the maker space has a small laser cutter I am trying to find something I can coat a board with and either burn away or melt onto the board to act as an etch resist.

Early attempts with paint had moderate results – our laser cutters on only 25W so it didn’t burn it cleanly.  I have heard that using flat black paint and a more powerful laser works.

Paste wax and markup fluid weren’t dark enough for the laser to vaporize (thinking of trying black crayons)

The latest attempt uses laser printer toner (just like the PNP only skipping the printing and iron on steps.)

The problem is how to get an even coat on a board without it blowing around.  Static electricity has potential (just like what they do inside a laser printer) but I don’t like the idea of a 5KV power supply exposed and handling powered toner is an automatic mess.

So for the first attempt I mixed the toner with rubbing alcohol (30% water).

Messy stuff!

I painted it on with the tongue depressor but it seemed to coat evenly and took only a few minutes to dry:

It mixes well and paints on fairly easily, here are some sample prints I did at various power and speed settings.  I cleaned the board fairly aggressively with paper towel and rubbing alcohol.

None are quite clean enough to become PCBs but they are getting close.

Although the toner paint looked dry, it may still have had some water in it.  I plan on trying a batch with denatured alcohol (100% – no water) and see if it works better.

 

2/16/2012

Updated progress

I have been trying a number of materials and methods to make my fast turn circuit boards.

I’ve decided that last toner is too messy and there are too many variables to create a repeatable process.  So now I’m trying various other masking materials:

 

Black and white spray paint – it works ok, but the ash left behind by the laser resists the etchant and leaves you with a poor etch.

I also tried tape:  Painters tape, electrical tape, clear and brown box tape.  The masking tape worked ok until the etch was slow and the tape started to dissolve.

I held a few of the boards up to the light so you can see how it etched:

 

 

 

 

 

 

One of the other members of the space found someone who had made the black paint work.  The process is to do 2 passes with the laser – the first burns off the paint, the second burns off the ash!  Then you wipe the board down with rubbing alcohol to clean off any residue.   Here is a set of 3 projects I lasered and etched at once:

This board turned out rather well, I had some trouble with the etchant taking for ever so lost some of the detail on the lettering, but the boards came out nicely.  I should get even better results on the next project.

In an attempt to speed the entire process up I tried to drill holes with the laser cutter from the back of the board:

   Not very good results!  After about 6 passes it still didn’t cut through thin PCB material and stunk and smoked the whole time!

 

 

 

 

 

 

So instead, I used the laser to cut wholes in a small piece of acrylic to use as drill guide:

 

 

 

This gives you a pattern to follow using a Dremel and the holes wind up in the right places and nicely lined up.  I drilled 2 holes in opposite corners of the board and used the leads from resistor to line up the template and board and hold them together while drilling.

 

 

 

This image shows the template attached to the board and about half the holes drilled.  This worked very nicely!  The only problems was small disks of acrylic getting stuck to the drill bit (you can see little craters on the left side of the board where these came from)  I had to clean the drill bit twice to drill the whole thing.  Either bigger holes or a different plastic might fix this.

 

This is first of the 3 boards I put together and it works just fine.  It is a level translator for the encoder you see in the holder.  The encoder will be attached to the drive motor in my electric car and feed back motor position to the controller.  The encoder is 5V and the controller wants a 15V signal.  The test bed uses a 15V power supply and LEDs on the 4 quaderature outputs.

Encoder test video

The Library

The Library

If you’re ever at the Milwaukee Makerspace and you hear someone say “It’s in the Library!” you might wonder to yourself (much like I did) why it’s called the Library.

Yes, we do have some books in there, but we’ve also got a giant wall of electronic components, as well as a sewing machine, embroidery machine, computers, projects, supplies, and miscellaneous junk.

I ran the question past Royce, and he had this to say:

It’s because we have a library of electronic components.

For example, if you are reading the Arduino Cookbook and a circuit in there calls for a 47uF capacitor or a 2N2222 transistor that you don’t have, you needn’t pay $5 shipping for a 50 cent part and wait three days to boot. It’s almost certainly in our parts library. Just go grab it!

We have most every value of through hole resistors and capacitors in a variety of working voltages. We also have common discrete silicon devices such as diodes and transistors. We are more limited on the ICs because of the colossal variations in ICs, but we have a lot of common beginner type stuff such linear power regulators, silicon controlled relays, 74 series logic, the venerable 555 timer, RS-232 level shifters and more.

So there you have it! Sure, there’s some books, but mainly it’s a “library of electronic components” which for a hackerspace, is a pretty awesome thing to have.

XBee Breakout Board

I recently purchased a couple of XBee modules from Sparkfun for a new project I’m working on.  I’ll be using them to send a wireless signal from an ice fishing tip up when a fish is on the line. I was frustrated after I received my XBee modules because I realized they do not fit into a standard breadboard!

After I got over the initial frustration I started designing a breakout board that would allow me to use the XBee modules with a breadboard. I used Dip Trace to design my first two sided board.

 

After I got everything laid out in Dip Trace I etched the board using the equipment at the makerspace. I used our standard process for etching the board.

  1. Print the board design on press and peel blue using a laser printer.
  2. Transfer the circuit design from the press and peel to the copper clad fiberglass board using a heated press.
  3. Etch the board in ferric chloride.
  4. Drill all of the pads with a #65 drill bit using a Dremel.

 

Here is the finished breakout board.

Smartboard Projector Project Abandoned

Back in August, Tom acquired several Smartboard-brand projectors and was interested in getting them to work as a normal projector would.  As you may recall from my original post on this project, these projectors will not display anything other than an error screen without their accompanying interactive whiteboards connected.

The original approach was to simply substitute my own video signal by swapping out some cables.  There is a dual-link DVI cable that attaches to the projector lamp assembly through the telescoping neck of the projector to its wall-mounted computer base, the Unifi 35.  I tried simply connecting a computer to the DVI connection on the lamp, but the lamp wouldn’t power on.  We eventually surmised that the lamp and the Unifi 35 were communicating somehow through the DVI cable and the lamp wouldn’t power on unless the computer detected that it was attached. Computers with DVI connections have the ability to detect when display devices are connected as well as instruct them to power on or off.

That led to trying to swap out individual pins in the cables.  I built three DVI breakout boards and set up a breadboard so I could mix and match pins from two sources and combine them to send on to the projector lamp.  I tried using the digital pins from my own source (a G5 Macintosh) and the analog pins from the Unifi 35.  After a lot of trial and error, it seemed the projector was communicating with the Unifi 35 somehow using either the analog pins on the DVI connection, the second digital link, or both.  Also, it seemed I could disconnect some pins after the projector was powered up, but I couldn’t start without them.  It looked something like this (table copied from Wikipedia):

Pin Description Purpose Required?
1 TMDS data 2− Digital red− (link 1) Required at all times
2 TMDS data 2+ Digital red+ (link 1) Required at all times
3 TMDS data 2/4 shield Required at all times?
4 TMDS data 4− Digital green− (link 2) Required at all times?
5 TMDS data 4+ Digital green+ (link 2) Required at all times?
6 DDC clock Required at startup only
7 DDC data Required at startup only
8 Analog vertical sync Required at startup only?
9 TMDS data 1− Digital green− (link 1) Required at all times
10 TMDS data 1+ Digital green+ (link 1) Required at all times
11 TMDS data 1/3 shield Required at all times?
12 TMDS data 3- Digital blue− (link 2) Required at all times?
13 TMDS data 3+ Digital blue+ (link 2) Required at all times?
14 +5 V Power for monitor when in standby Not required?
15 Ground Return for pin 14 and analog sync Not required?
16 Hot plug detect Not required?
17 TMDS data 0− Digital blue− (link 1) and digital sync Required at all times
18 TMDS data 0+ Digital blue+ (link 1) and digital sync Required at all times
19 TMDS data 0/5 shield Required at all times?
20 TMDS data 5− Digital red− (link 2) Required at all times?
21 TMDS data 5+ Digital red+ (link 2) Required at all times?
22 TMDS clock shield Required at all times?
23 TMDS clock+ Digital clock+ (links 1 and 2) Required at all times?
24 TMDS clock− Digital clock− (links 1 and 2) Required at all times?
C1 Analog red Required at startup only
C2 Analog green Required at startup only
C3 Analog blue Required at startup only
C4 Analog horizontal sync Required at startup only
C5 Analog ground Return for R, G, and B signals Required at startup only

After a lot of trial and error, I didn’t seem to be much closer to the goal of getting my own video source to display.  I also began to consider that the manufacturer may have switched around some pins between the Unifi 35 and the projector to prevent consumers from servicing the unit.  The DVI cable I was working with was internal to the machine after all.  There’s no reason any one would ever try to connect their computer’s DVI output to the lamp itself.  Signals leaving the Unifi 35 could be sent on a different pin than the DVI standard suggests and then rearranged back into the standard configuration at the lamp assembly.  I never really dismissed that possibility, but I also didn’t see much to support it.

I trudged on and hooked up an oscilloscope to monitor was was going on with the analog pins, C1 through C5, because they seemed to be critical to the lamp turning on, but not necessarily staying on. This is what I found:

Pin Description In Standby Mode Once Powered On
C1 Analog red 0v constant +3.3v constant:
C2 Analog green +5v constant +5v constant for 0.93 seconds every second then a brief flash for 0.07 seconds of this waveform:

+5v (58% of the time)
0v (42% of the time)
at ~1.2 kHz
C3 Analog blue +5v constant +5v constant for 0.93 seconds every second then a brief flash for 0.07 seconds of this waveform:

~0v and a more complex pattern (0.8 ms/3.5 ms)
+5v (0.8 ms/3.5 ms)
~0v and a more complex pattern (1.1 ms/3.5 ms)
+5v (0.8 ms/3.5 ms)
at ~285 Hz
C4 Analog horizontal sync 0v constant 0v constant for 0.93 seconds every second then a brief flash for 0.07 seconds of this waveform:
C5 Analog ground Reference for all Reference for all

Unsure of what these signals represented, I consulted with Royce, Tom, and a few others and worked up the courage to use a logic analyzer for the first time.  Most of the work was wiring the thing up and assigning names to the leads in the software.  My breakout boards turned out to be more fragile than I expected so I ended up resoldering a all of the flaky connections.  The Intronix 34-channel Logicport Analyzer is pretty slick and comes with some great software tutorials.  Once I got it going, it was fairly straight forward.  I can definitely see how this device can come in handy now that I’ve used it.

One of the first problems I ran into was the multitude of different voltages at work.  The Logicport software has a logic voltage threshold setting to help weed out logic from other signals, but I found myself dealing with signals less than 0v, as well as +3.3v, and +5.0v.  I eventually scanned the spectrum and sat, clicking the threshold up in small intervals of 0.05v, and watched to see if anything appeared on the screen.  It would seem that while in standby mode, some of the the TMDS data pins and the DDC clock and data pins are held above +2.0v.  Around 0.0v, some of the data shields show some variation between low and high during standby but as the projector is starting up, there are definite patterns on TMDS data shields 2/4, 0/5, and the clock shield.  TMDS link 1 shows some activity during startup in the +3.3v range and then shortly after link 2 does as well as the analog red pin.  Why a digital signal might appear on the analog pin is unclear.  I could be measuring it wrong also, but there does appear to be a signal there.  I also checked the analog pins during standby against what I saw with the oscilloscope and the numbers seem to agree except that the C4 horizontal analog sync pin showed voltage at or above +2.00v with the analyzer when the oscilloscope showed no voltage difference at all.

Since I was more interested in the control data than the video data, I focused my attention to the DDC clock and data pins to see if I could decipher how the projector and Unifi 35 were talking to each other.  PC monitors and projectors with DVI connections use a display data channel (DDC) and a standard called I2C (I squared C).  I found some great information on I2C and DDC protocols online here and here.  At +5.00v I read a portion of the communication between the Unifi 35 and the projector and tried to analyze it.  Unfortunately, the data doesn’t seem to follow what I’ve read on the I2C standard. The clock rises and falls unexpectedly, the start/stop commands don’t appear where I would expect them to, nothing resembles a 7-bit device address and there is seemingly no pattern to data.  The other logic analyzer screenshots can be found here.

We considered trying to spoof the USB connection to the whiteboard at one point, but that seemed to be problematic also.  I set up the logic analyzer and monitored the USB connection, but to no avail.  It’s possible that without the board to receive power from the USB port, there’s no way of telling how the board would communicate with the Unifi 35 and projector.  In a last ditch effort some weeks ago, I contacted Smart Technologies, makers of these products, and flat out asked them if the projectors could be used without the whiteboards.  The answer was, unfortunately, no.

I began to lose interest after this and once I got back to the project after the holidays, I decided to finally give up on it.  I would rather use my time on other projects.  It was by no means a waste as I gained more experience etching my own circuit boards, soldering annoying small connections, and I got comfortable with the logic analyzer; assuming I used it right.  I also became wary of computer cable vendors on Amazon.com.  During the project I needed some dual-link DVI cables, but when my order showed up, the second data link pins (the six in the middle of the connector) weren’t even wired.  I stuck a multimeter to them and found continuity on all but those six pins.  Needless to say, I left them some grumpy feedback and got a refund.  Thanks to everyone who helped and gave me advice.  As Shane said, “I doubt anyone else would have gone this far.”  I took that as a compliment.

Food Not Bombs Bronze Pendant and Final Star Trek Assembly

Previously I had blogged about a Star Trek logo that I cast as gift for my sister-in-law. I’ll update that project later in the post, however, I held a second casting back from the blog as it was intended as a gift for my wife.

For a couple of years my wife co-ran Milwaukee’s Food Not Bombs movement. She has always had fond memories of that time and has on more than one occasion brought up their logo: a hand clutching a carrot. So, I decided to make her a pendant with a relieved carving of that logo. To begin with I pulled the jpg logo into Inkscape loaded with the Better Better DXF Output plugin. I used the Inkscape drawing primitives to trace over the major outlines of the logo and then export the tracing to DXF. Once in DXF I imported the file into CamBam where I cleaned of the drawing a little more and defined machining operations for our CNC Router to perform. I turned the outlines into a series of adjacent polygons. (e.g. a wrist polygon, a thumb polygon, etc.) I then setup pocket operations of varying depths on each polygon. Finally, I exported the file to G-Code for consumption by the Mach 3 router control program.

FNB Logo in Mach 3If you look you can kind of see the polygons even if the depth setting of each pocket is not apparent.

Above you can see the pendant in the process of being routed out and also the finished wax mold after routing. Below you can see the pendant after casting! She loved it and wears it frequently. I was a really good feeling to actually put some effort into making a gift this year. It made the act of giving the gift that much more special.

I also completed the Star Trek logo. I turned that into a broach.

Above you can see that I have mounted the Star Trek logo to a plastic backing. I’ve also cut one of Adafruit’s EL Panels way down in size and hooked it up to another one of her small inverters. The small inverter normally cannot run her panels, but after being cut down so much, it wasn’t a problem. Below you can see the two pieces put together.

And finally the finished gift!

As I said, I really enjoyed giving gifts that I made this year. I am going to try to do more of that!