Category: Building

Surgery on my baby

Yesterday my projector was acting up in a very unfriendly way. There was something wrong with the lighting. It was uneven with a couple lines through it. Worse, when I moved the projector, the lines moved, and I could hear a part moving around inside. Eventually, percussive maintenance no longer affected any change in the image. My only real option was to take it apart. Projectors aren’t cheap, and they are built of complicated and sensitive parts, so I was reluctant to open it up. My first thought was a flaw in the light bulb. I took the bulb out and examined it, cleaned out some of the accumulated dust, and tried again. No luck. Then I removed the case to expose the inner workings. I couldn’t see any problems immediately, but I wasn’t exactly sure what I was looking for. Since it was approaching 2am, I decided to call it a night and worry about it the next day. Just in case, I ordered a new bulb, which will be delivered early next week. It turned out that the bulb was not the problem, but it’s too late to cancel the order, and it will be nice to have a backup bulb anyway.

Today I decided to give it another try. I dismantled it again, and this time turned it on while dismantled. It is incredible how much light comes through a tiny aperture. I could not look at it without some kind of protection. By following the light path, I was able to discover the problem.

The light goes through a very small square, perhaps half a centimeter wide. It enters this light tube composed of four small rectangular mirrors. The tube is about 3 centimeters long, and the four mirrors are attached along the long edges with some sort of glue. What had happened was that the heat from the lamp had weakened the glue, and one of the four sides of the square had dislodged. This led to the dimming because the mirror was no longer directing the light, and it explained the lines because the mirror was partially in the path of the light.

I was able to extract the square and, using scotch tape (bless the stuff), reconstruct the square tube and replace the fourth side. I am concerned that the scotch tape will melt or otherwise not hold, but if that happens I’ll look for a more formidable adhesive. I put everything back together, and my projector worked as well as it ever had.

It was a little intimidating working with an expensive piece of equipment whose mechanisms were mostly unfamiliar to me, but I’m glad that I was able to figure it out and fix it without damage.

Computer Lights Show

Back in college I occasionally did DJ gigs. It was a lot of fun and I did some pretty neat things to make it easier. I had a remote control for my WinTV card and I remapped the buttons to control WinAmp, so I could control the music while I was dancing on the floor. Another thing I did was build some lights for inside my computer case.

When I originally built it, the lights were controlled by the internal serial port, and I wrote some software to advance the lights. I was even able to integrate the sound volume into it and had some rudimentary beat detection going so that the lights would change on the beat. Unfortunately, the system slowly degraded over time. The first problem was that the beat detection didn’t work when I upgraded from Windows ME to Windows XP. The next problem was that the external power supply died. Finally, I switched to Linux, so the software I had written to control it wouldn’t work.

In January 2007 I cleaned things up quite a bit. First, I connected the power to the computer’s power supply, thus removing the dependence on an external plug. Next, I set it up with a 555 timer chip and inserted a potentiometer to vary the speed of the flashing. I had to replace a light bulb, but the refurbishing took only a few hours. Now it seems to be working fairly well. See the pics and the video. There are 5 lights throughout the case, and they flash in order.

The circuitry is very simple. I have a decade counter which increments every time it gets a pulse. Each time it increments it turns on a different transistor, which powers a different light. On pin 6 it goes to the reset pin so that the decade counter only counts 1-5 over and over again. The 555 timer provides the pulse to the decade counter. If you want more details about the circuitry, contact me.

Video of the computer lights show in action (Windows Media Video (WMV) format, no audio)

 

Bob Baddeley Memorial Fountain

At the lab a model of the campus additions was placed on display in each of the buildings so that people could get an idea of how the campus was going to change. One day I made a little addition to the model. It stayed up for at least 4 months and moved from building to building. Take a fast look at workbootsnerd.com for an insight on the construction process.

The addition was the “Bob Baddeley Memorial Fountain,” and it was placed right in the middle of the display. It was made out of green cellophane taped to a piece of colored cardboard that was taped onto the piece of paper labeling it the memorial fountain, which was then taped to the display. I managed to get the scale believable, and the fountain just blended in with the rest of the display. At first I was sure it would disappear and I would get in trouble. After a few days, the display disappeared from my building. Later I got a message from a friend in another building asking me if I knew about it, because the display had been moved to his building and he had recognized the name. I knew about the display moving to two other buildings after that, and I never heard from anyone about it. I walked by it a few months later and it was still there.

I have been asked why it’s the Memorial fountain, as I’m not dead. My answer is two-fold: if I had been discovered by the wrong people, I might have been dead, and this way I can say it was a joke ahead of its time. I was also asked why I used my real name. In retrospect, I should have picked a more clever name, like a famous scientist or a random person. Oh well,

Audio Switch

I have a set of speakers that I embedded into my coffee table. This actually made a lot of sense because it moved the speakers to the center of the room and away from the apartment walls and increased the stereo effect, as well as saving room in the cramped apartment. The speakers serve both my computer and my Playstation2. The speakers only have a single 1/8” plug, though, so I built a switch using a tin of mints (the mints were horrible anyway) that accepts the speaker plug and the plugs for the computer and the Playstation2. It’s a cute little thing and does exactly what I needed.

Steadicam

My digital camera needed some accessories, and the steadicam seemed like a perfect addition. Built out of simple parts from a hardware store (and a pie plate from ShopKo), this steadicam makes sure that while I’m taking video the camera stays level and steady.

The pictures should be pretty self-explanatory as far as building it. We were making two at once, so there’s twice as many parts as you’ll need. The parts can be acquired at most hardware stores. The purpose of the pie plate is to create a wide surface so that the steadicam can be set down and used like a tripod without tipping over. It works surprisingly well. One thing that is different from the pictures is that we discovered that the plastic screws were too wobbly, so we went with metal screws instead. The plastic wing nuts are still fine, though.

Composite to S-Video

With the projector in my apartment, I have a VGA cable and an S-Video cable running as inputs. However, my Playstation2 cable only has composite video output. It turns out that composite can be hacked into s-video fairly easily. By running the composite video signal to both the brightness and color parts of the s-video you get a usable video feed. It’s not great quality, but it’s better than nothing. I also managed to find a Playstation2 cable that had s-video out, so it’s no longer an issue, but for a while I needed a solution.

Staples Easy Button Hacking

For a project at work I needed a solid button that would be easy to press. It turned out that the Staples Easy Button was a perfect match for what I needed; heavy, easy to locate without looking for it, a great size, and it was just a single button. I opened it up and removed the speakers and disconnected the majority of the inner workings, rewiring some bits so that I could run a wire out of it and into the serial port of a computer. Then I could use the button as an input device. It worked perfectly.

Here is a step-by-step gallery that shows how to dismantle the button, remove the speakers (you could leave them in, but what’s the point? Why not take out the free speaker for use somewhere else?), tap into the switch, and re-assemble.

We start by removing screws. Keep removing screws until you can pry the speaker out. Cut the red wires and remove the speaker. Reassemble the button most of the way. Remove the resistor on top. Also cut the black and white wire coming from the battery case. Cut the traces to the chip (the black mound). Solder wires at the points shown on the images: there’s one point where the resistor used to be, and one point that’s just a bare hole. Then solder the other ends of those wires to the black and white battery wires. Now reassemble completely. You can now tie or solder wires to the pads where the batteries go and use the button for whatever application you have.

OLD Personal Projects

In high school I played around in my basement bedroom a lot. I discovered some neat things, some things that I still can’t explain, and some very useful things.

One thing I worked on was a sound system. I found a couple speakers and a really old amplifier at Goodwill and rigged them together. The sound quality wasn’t professional, but it was more than enough to do what I wanted. It wasn’t even stereo, but I could get it loud. Then I took apart an alarm clock and rewired the speaker output into the sound system. Occasionally I would have the amplifier volume a little loud and I would wake up EVERYBODY in the house at 6am for school. Later I took my 386 computer apart and wired the internal speaker output to the amp. The computer didn’t have a sound card, so this was my only option.

Another thing I played with was input devices. I took a keyboard apart and tapped into the wires for the arrow keys. Then I took apart two pens and taped them so they were perpendicular to each other. I put a small piece of metal in each that would slide around easily. Then I taped paper clips on each end so that the pieces of metal would make two separate paper clips touch and complete a circuit. The circuit it would complete was the arrow key. I then attached this small contraption to a glove. The end result was a motion sensitive glove that could tell whether my hand was tilted forward, backwards, left, or right, and would send the appropriate arrow key through the keyboard to the computer. It was the cheapest glove ever.

One of my experiments involved plugging a socket into a bucket of water. Bubbles of hydrogen and oxygen appeared at the terminals. After a few days, so much of the wire had corroded that the tub was blue-green with copper. There wasn’t really a point to all of it, just the coolness of seeing science doing what it was supposed to.