Building – Bob Baddeley

Side project – Mallards Fast Pitch

My hackerspace Sector67 was approached this winter with a problem; the local minor league baseball stadium (Madison Mallards) fast pitch sign was old and no longer working, and they wanted some help fixing it up. In exchange for our expertise, they promised significant advertising and publicity, and they would have us be special guests at a ‘maker’ day during the season.

For the impatient, here’s the finished product:

We took them up on the offer and had a field trip to the stadium to see what was already there. There are two main parts to this project. First, there’s the sign itself. Second, there’s the press box, where the radar gun and the sign controller sit. The previous method was to have the person running the scoreboard watch the radar gun and type the speed onto a controller. There was no accounting for the angle of the radar gun, and it required a person to act as the middle man. They wanted to automate this part of the process. With the sign, they wanted it to work again. After seeing their existing setup, it didn’t take long for us to decide they needed an upgrade and we would start from scratch.

The sign in right field. Doesn't look very big from this shot, but it's legible from the far side of the stands. — The sign in right field. Doesn’t look very big from this shot, but it’s legible from the far side of the stands.

Up close you can see it's a bunch of incandescent bulbs. They're not even covered! I wouldn't want to run into that sign while catching a ball. — Up close you can see it’s a bunch of incandescent bulbs. They’re not even covered! I wouldn’t want to run into that sign while catching a ball.

The electronics controlling the sign. This is basic and ancient stuff here.

Up in the press box, this is what controls the sign.

This is the radar gun. They have to charge up the battery (the handle) before every game. This is a pain.

The stadium let us borrow the radar gun, the only part of the process we intended to keep. Reverse engineering it wasn’t too bad. We were able to find a manual and figure out that the three pins coming out into the handle were two for the battery and one for a serial signal. Once we connected to this signal, it was trivial to decipher it (9600 baud ASCII text). We designed a 3D printed part that would take the place of the handle and supply power to the radar gun as well as grab the serial signal.

Yes, those are nails. They worked perfect.

After that was the box to replace the controller. This box would read in the serial signal, compensate for the angle, and send out a signal to the sign. At first we played with XBee for a wireless transfer. This ended up being so unreliable and so difficult to get set up that we decided to give up. Besides, long term support is important for this kind of a project, and something wireless is a lot more difficult to diagnose and debug than wired. So we went with RS485, which is perfect for long distances, and there was already a pre-existing cable from the previous sign. I threw in a screen and some buttons for good measure (to let the user adjust the angle), and a switch to turn it all on, and we were good to go. Now the only thing a user has to do is flip the switch to turn it on, then push the power button on the radar gun, and it works.

The view from the press box. The radar gun captures every pitch, the controller box is mounted on the wall, and the previous controller is wrapped up on the desk.

The controller box. There's a screen, buttons, and power switch. The cables are for power in, power/serial to the radar gun, and RS485 out to the sign. — The controller box. There’s a screen, buttons, and power switch. The cables are for power in, power/serial to the radar gun, and RS485 out to the sign.

Inside the controller. An arduino with LCD/button shield, a RS485 breakout, and wires.

Next was coming up with a sign. We’ve used the P10 red LED modules before on the bar bike, so we had some experience. For this one we purchased the outdoor waterproof ones. We also got power supplies and a controller card. There is some code on the web for controlling these guys directly, but it’s a lot of work and I didn’t have the time or inclination to figure it out. So we went with the controller card. I should note that the prices for these parts is ridiculously cheap. The LED modules are $6.50, the power supplies are $8, and the controller card was $50. So we had all the major components for the sign for just a few hundred dollars, and that’s because we ordered extras of everything in case of failures. We designed and cut an enclosure and attached the modules to the frame, then wired everything up. The wiring is simple; power up each column, data across each row. Two power supplies power two columns each.

Behind the sign. Two power supplies, one laptop, a controller card and hub, and a laptop. The sign is 6 rows and 4 columns, giving us a resolution of 128x96 — Behind the sign. Two power supplies, one laptop, a controller card and hub, and a laptop. The sign is 6 rows and 4 columns, giving us a resolution of 128×96

Getting the controller card working was tricky, though. There is no documentation on the protocol, so I tried sniffing the packets being sent to it, but couldn’t make sense of them. There was no API, and after repeatedly pressing the Chinese company for resources, they sent some sample code and a dll, but it would only work on windows. We were trying to avoid Windows and go with a cheap (and low power) linux PC or Raspberry Pi, but in the interest of time, we ended up bailing on that and just getting a very old and cheap Windows XP laptop. Fortunately, it had a serial port, so we could hook a RS485 to RS232 converter to it and we were able to communicate quickly with the press box.

The controller card comes with some windows software for setting up the sign and displaying content, but it was difficult to get it to show real time data. What we ended up doing was writing a python script which would monitor the serial port and upon receiving a speed would write that speed to a file. One of the options in the other software for controlling the sign (called LEDSHOWT9), was to display the contents of a file, and update every N seconds. So we picked that option. Now every few seconds LEDSHOWT9 will look at the file, and take the contents (either the speed or a blank), and show that on the sign. Tada! It’s a hack, but it works. If inclined, maybe I’ll write up something better and do animations or something. But probably not.

Here’s the final product.

Clearly visible during the day from the stands. Pretty font, works automatically. Complete success.

A Kalahari Christmas

After Erin took me on a ski trip to Salt Lake City for Christmas 2010, I was far behind in the Christmas Karma. For 2011 I planned to take her to a resort in Wisconsin Dells, which is sort of like the Las Vegas of Wisconsin, except with water parks instead of casinos. Of the many resorts, I decided on Kalahari based on recommendations of others and some research on the web. But just telling her wasn’t a great way to do the presentation. I wanted her to unwrap something.

I’ve been working for a while on a portable electronic scoreboard, so I had all the materials to make a good LED sign with the name. The day before we were to leave for Kansas, I started the project. The idea was to make a big LED sign that said Kalahari on it. It would be battery powered, and a switch would turn it on when the box was opened so that it wasn’t on the entire time and running out of battery. That was as far as I got in planning before I started building.

I borrowed a rechargeable battery from Sector67 to use as the power supply, then laid out the LEDs on a prototyping perf board covered with sticky black nylon paper. It took a couple tries to get it all to fit on the available board with legible letters and decent spacing. Then I found a switch that would work. The circuit was simple. The switch connected the + voltage to the board and the ground went directly to the board. The LEDs were connected with a resistor and two LEDs in series, and all those strings were in parallel. This meant a huge current drain, but I was limited to a power supply with only 6 volts, so I didn’t have much choice. This also meant a LOT of soldering and a lot of current limiting resistors. There was an odd number of LEDs, so I put an extra one on the back side so that the circuits were all the same.

With all these LEDs packed into a small space, it was very bright, so I struggled with a few different ways to do the presentation. I ended up taping the board behind a piece of paper so that the paper would diffuse the light a little. It ended up working great. The paper covered everything, including the switch. When the box was closed it was off, and when it was opened the switch was triggered, turning on the sign.

The girlfriend was happy, so the project was a success.

The next time I do something like this I’ll use less LEDs and instead of doing a sign of LEDs I think it would be better to have a piece that had letters cut out and was backlit by only a few LEDs. I also would have spent a lot more time on what was surrounding the sign. Using regular paper and crayon to draw was the best I could do with the limited time and resources I had, but it wasn’t enough for me. Construction took far longer than I expected, and I was a little disappointed with the results. I was working late into the night to solder it all together, and I barely had any time to work on the rest of the package. I can do better.

Fast Scanner

Since I’m moving in a few months to an apartment of significantly reduced size, I am starting to reduce the size of my collection of stuff. One thing I’ve been carrying around is everything from my college career. I have every syllabus, paper, homework assignment, handout, midterm… in total it was three boxes full of binders. This represents tens of thousands of dollars of education, though, and I wasn’t entirely willing to part with it. I started scanning pages with a scanner. I had a process that was giving me up to 6 scans per minute. The quality of the scans was good, but the speed was not fast enough, and there were too many manual parts to the process. I needed something faster.

I realized that a photo of a piece of paper would be faster than having a scanner do it, and if lit well enough and with a good enough lens, it would be just as good as a scanner. I rigged up a tripod with an extended arm to hold my camera, and I put a white background on the desk and marked some lines where the paper needed to be to be in the shot. Since I don’t have a fancy DSLR with a remote, and pressing the button manually was way too much effort and moved the camera around too much, I rigged up a piece of twine so that by pulling down on the twine I could get the camera to take a shot. I tried pulling the string for a while, which was pretty fast, but still not as efficient as possible. I tied the twine to a ruler and used the ruler as a foot pedal, giving me both hands to move the pieces of paper as quickly as possible. The light sources were just regular white compact fluorescent bulbs, placed to put as much light on the paper as evenly as possible.

The resulting contraption bumped my speed up to 15 pages per minute on average. Sometimes it was higher depending on if I was dealing with loose notes or stapled sheets. Having the shutter controlled by my feet gave me a huge advantage, and I was able to fly through all 3 boxes of papers in a few evenings much faster than I expected. Now I have it all on my computer, which should probably still be sorted, but at least it’s not taking up any physical space, and I don’t have to feel any sense of loss when I recycle my stacks of papers.

Mouse Modding

Last night I made some changes to my mouse; we’ll see if they’re improvements or not. Originally I was dismantling it to clean it. Something had gotten inside the wheel and was causing it to scroll inconsistently. Once I got inside, though, I saw an opportunity to tune it.

First was the clicking on the wheel. This is accomplished with a spring, and is sometimes annoying, especially since I like to give my scroll wheel big long spins to quickly move around on a page. Removing the spring was pretty easy.

Second, I noticed a weight added to the inside. I’m not entirely sure what the weight accomplishes, other than making the mouse that much harder to move, so I took it out, too.

If I need, I can easily put the parts back in, but at the moment I’m rocking a lighter, smoother mouse.

Broken Car Lock

It’s no secret that I love my car. It’s been extremely dependable, has treated me very well, has a good personality and an adventurous attitude, and doesn’t ask for much (it’s a 2000 Chrysler Neon, and yes, I mean Chrysler). I’ve had it for almost 10 years and put over 100,000 miles on it myself in addition to the 20,000 that were on it when I got it used. If I were to get another car, I’d look for something exactly like the one I have.

But once in a great while it will have small issues. Once a wiring harness broke loose and cause the rear lights to go out. Other than that, it’s worked very well and could probably go for another hundred thousand miles without problem.

About a week ago I put my key in the door to unlock it and found that it turned freely. I had to unlock the passenger side and then unlock the driver side from the inside. For a few days I drove around without locking the door. Monday I finally got an opportunity to examine the problem. I was able to disassemble the door relatively easily. It was fairly straightforward except for the part where the window handle was connected, but I managed to find the service manual online and pop the handle off. Then I could get in to the lock mechanism and see where the problem was. It didn’t take long to discover the problem. The rod that connects the lock mechanism to the key had slipped off. The piece that held it on was missing. Figuring it was probably at the bottom of the door frame, I felt around and identified it. Yep, there was the problem.

That piece should be symmetrical. The piece that had broken was about 2 millimeters wide and because of that the thing slipped off the lock and was no longer holding the rod in place. It didn’t take much jostling for the rod to fall out.

I didn’t have any parts exactly like that, and I was up to the challenge of fixing it with parts that I had around the house. I made a crude washer out of a piece of scrap tin from a can. Then I made a springy curl of stiff wire that would take the place of the part that broke. I installed onto the lock mechanism and played with it a little to make sure it was stuck pretty well. I tried to take it off to adjust it a little, but couldn’t even get it off without some serious effort, so I just left it on there. I tested it thoroughly before putting the door back together. With the door completely reassembled, I tested it out some more, and it worked exactly like it had originally worked.

I’m kind of glad that my car is mostly mechanical and doesn’t have a lot of electronic parts. Electronic locks or windows would have made this a much more difficult operation. I’m also happy that I was able to build the parts that I needed from scratch and basic tools. Plus, I always enjoy doing things with my hands and seeing the results and saving money in the process.

Camera Troubles

Erin handed me a camera a week ago that had gone through some tough times. It had been dropped while on, and the lens assembly was broken and askew. The camera couldn’t recover from it on its own, and so I was brought in to see if I could fix it. Having been able to revive Erin’s camera, which had the misfortune of a drop into sand, and having removed dust from my own camera many times, I took on the job. Since it was already broken, the owner of the camera didn’t have any expectations of getting it back anyway, so it was a riskless job. The first image is of the camera, though the lens problem is not visible.

Taking the camera apart was not difficult. There were lots of tiny screws, but for the most part the pieces separated fairly easily. Of course, as I did it I learned little bits about the assembly that made taking it apart easier. The second picture shows the partially disassembled camera. The lens assembly came out without any screws.

The lens assembly out, I was able to partially disassemble it as well. There were two main lenses. The first was the big one in the picture below. The second was the small one in the picture below that. Both were capable of moving.

In fact, it was the plastic on the smaller lens that had broken, and was sticking out, preventing the lens assembly from closing back up. This little piece of plastic, which is the part closest to the camera, turned out to be extremely important. I tried at first to just remove it and reassemble the camera, but it turned out that it wouldn’t focus without it. The piece was essential for guiding the lens forward and back and without it a small spring was pulling it in a direction it shouldn’t have gone. I was able to super glue it back together, but then had to take a small file to remove small jutting slivers that were adding too much friction to the assembly. The hardest part was putting the whole lens assembly together and back apart over and over, which took many minutes each time, and put wear and tear on some components that were only ever meant to be assembled once. In fact, a great deal of time was spent maintaining and guiding parts back together, and resetting springs that had to be unset.

I thought that I had been successful and had fixed the camera, but there was a problem. When I took a photo, the iris would stay closed, and it wasn’t until I would dismantle the whole thing that I could reopen the iris. Clearly this would not work in the field. I had to dismantle the assembly further to discover another unfortunate break.

The iris is controlled by two extremely small electromagnets, which apply torque to two magnets, which have small arms at the end of them. Those arms push and pull the thin pieces of plastic over the lens to adjust the light levels. Unfortunately, one of the arms was broken on the small magnet.

This was the deal breaker. Without the arm, the iris wouldn’t function properly, and the images would be overexposed (or possibly underexposed). The magnet wouldn’t take to super glue, and even the process of gluing was made more difficult by the fact that all my tools were metallic and would move the magnets as soon as they got near. For a sense of scale, the pic below is of an object that’s 4mm long at its longest

It took a lot of time to work on the camera and figure out how it all fit together. There were a lot of little pieces that had to be assembled just so, and it’s such a shame that the camera is perfectly good except for a few misplaced atoms, and because I won’t be able to find a replacement will now likely be discarded in its entirety.

TV Remote Alarm

We had an interesting problem at work. There’s a display in the main lobby of my building that shows the calendar of all the conference rooms and a map showing where they are in the building. It’s pretty handy for visitors and looks really slick. The problem, though, is night. There’s no point in having the display running 24/7. But the TV has a flaw where it won’t go into sleep mode when the HDMI cable is plugged in, even if the computer itself is asleep and there isn’t a signal.

The solution so far has been for a select few to turn it on in the morning when they arrive and off when they leave. Naturally, this isn’t a sustainable or reliable solution, as it doesn’t take a lot for the system to break down.

So Ian brought me in on the problem to see what I could do with it. I thought about some existing options. An outlet timer would work for turning it off in the evening, but not for turning it on in the morning (it would give the TV power, but not turn it on). I even found an alarm clock that was capable of being programmed to turn on and off a TV, which was really close to what we wanted, but it was discontinued, and reading into the manual it looked like it wasn’t going to work anyway.

I realized I would have to build something. I started off thinking of building off of the Arduino microcontroller board, which I’ve used for other projects and really enjoy using. I spent a day working on hooking up an infrared LED and trying to get it to output a standard on/off signal that the TV would recognize. I also tried to hook up an LCD screen and buttons for configuring the timer, but I quickly got frustrated as each part took way longer than I wanted, and wasn’t getting anywhere.

It made a lot more sense to work with existing electronics and cobble something together. It turned out I already had an alarm clock that I had stopped using in favor of my cell phone, and the alarm clock had two configurable alarms on it. And Ian had purchased for me a cheap universal remote. So I just had to get the alarm clock to trigger the remote control.

This was easier said than done. First I took apart the remote control. I followed the traces back from the on/off button and soldered a couple wires to them, then fed them out the back of the remote through a hole where the battery cover was. Next, I opened the alarm clock and went about trying to identify triggers I could use to determine the alarm state. I was hoping for something simple, like one node being +5V when the radio alarm was on and a different node being +5V when the buzzer alarm was on. Sadly, there was no such luck.

I’ll spare most of the details, but I never found a clean signal I could use. I ended up taking the radio alarm, cutting out the speaker, turning the volume all the way up, and using the speaker wire to drive two relays, which triggered the remote, then also fed to the alarm reset button. That way the radio would turn on, the signal would trip the remote, and it would reset the alarm. That one worked pretty slick.

It was even harder for the buzzer alarm. Not only could I not find a signal, but it didn’t go to the speaker, either. It went to a separate piezoelectric speaker, and the voltage to it wasn’t enough to trip the relays. So I had to build an amplifier circuit that bumped the signal up to something that would trip the relay. But then there was another problem. It was tripping the alarm reset button faster than it was tripping the remote, so it’d reset the alarm before the remote control had a chance, and the TV wouldn’t ever get switched. I fixed this by putting in an RC delay circuit on the alarm reset relay.

I put it all back together and tested it out. It’s in my apartment, so I had to try it out on the VCR (I had to take it out of its box), but it worked. The alarm clock dutifully turned off and on the VCR at the right times.

I’m bringing it in to work tomorrow to see if it’ll work on the intended television. It’ll probably sit on a counter across the lobby and point at the TV, and definitely have a sign that says what it is so people don’t get suspicious.

Here’s a picture of the completed project. I won’t show the insides because I’m a little embarrassed of the circuit. I could have done a much cleaner and more correct design, but it works now, so I’m happy. I hope people at work appreciate it, too.

Hard Drive Surgery

A friend of mine recently had a minor emergency when a portable hard drive was knocked off a table and ceased to function. I was called in to help. Indeed, it did not work. When plugged in (and I tried on multiple computers and operating systems), it wouldn’t be able to recognize the device.

Since there was nothing I could do externally, I opened up the case, careful to make sure that anything I did could be undone. The case wasn’t even screwed together; it was two pieces of plastic that snapped together. After unsnapping all the way around, the hard drive was exposed. Again, no screws. It was held fast with some rubber strips on the corners. There was a piece of aluminum foil covering the electronics, so I carefully peeled that back. Glancing at the board, I didn’t see anything wrong immediately. The board was attached to the hard drive, and was easy to pull off. It turned out, the hard drive was a standard SATA connection, so I turned off my computer, plugged it in, and turned the computer on. It had no problem recognizing the hard drive and mounting it. I created a folder on my computer and immediately copied all the files over without any problems. Next I compared the file sizes to make sure I had gotten all the files and they added up to the right size. After that, I turned off the computer and removed the hard drive.

Looking again at the board, I noticed a small part near the USB connection that was askew. Looking more closely, it was indeed broken off the board and hanging by only one of the four solder points. The board was so small, though, and the connections tiny. I tried heating up the soldering iron and getting in there, but there was no way I’d be able to resolder it on. Just too small. I told my friend the data was fine and that the board was not and that if she got another portable hard drive I could copy the files over to it.

She brought me a new portable hard drive, so I plugged it in, copied the files, checked the size to make sure it was all copied, and unplugged it. Then I brought her the new hard drive, the old one, and showed her the parts and what had happened. Since the hard drive was still good, it didn’t make sense to discard it. It’s a 120GB laptop hard drive. She’s going to confirm that everything is there, and then I’ll delete the copy of the data I have on my hard drive.

The whole operation was surprisingly easy, and it certainly helped that the portable hard drive was so simply designed and used standard connections. I’m glad we were able to recover everything, though a little disappointed I couldn’t resolder the part back on.

Going green(er)

I’ve always thought that I am pretty good about doing things in a decently Earth-friendly way. I keep my AC and heat at barely tolerable levels, I recycle, I turn off the lights when I’m not in the room, I turn off the water when I’m brushing my teeth, and I carpool when it makes sense. But I recently read the book //Hot, Flat, and Crowded// by Thomas Friedman, and while it’s a very good book, it scared me pretty good. So I’ve resolved to do even more to reduce my energy usage, carbon footprint, and resource usage. I’ve been doing some experiments around the apartment, and I’ve tried a few things out, and I think I’ve come up with some more reasonable things I can do to save. Plus, I’m saving money this way, which is a bonus.

* Unplugged lights. People have said before that my place is pretty dark. Now it’s even more true. My bedroom is lit with a single 23 watt compact fluorescent bulb, and I’ve unscrewed half the lights in my dining room and bathroom. It’s enough to see clearly, and it’s not as dark as having candles. Plus, even though I was already turning off the lights when I left the room, having only half of them on when I’m in the room means a reduction of energy by 50%!
* Unplugged peripherals. A huge drain on the power grid is devices that are in standby. So I unplug my microwave except when I’m using it, and I use my cell phone as my alarm clock and no longer use a standalone alarm clock.
* Turned down the heat even more. For a couple days I turned it off entirely. However, when my fingers got too cold to let me type, and I started to get sick, I decided that going without heat entirely wasn’t an acceptable option. I did turn it down a couple degrees, though, to 62. Cold enough that I can’t lounge around in shorts and a t-shirt, but not so bad that I can’t type.
* Turning my desktop computer off or putting it in standby. For years I’ve run my desktop computer 24/7 because it acts as a server. I’m now trying to move those services off my computer and onto hosted servers or finding alternatives. Now I can have my computer off or in standby most of the time.

These simple things should reduce my electricity consumption even more. I’ve saved my utility bills every month, and created a graph that shows my power usage each month:

There are some obvious things to note about this graph. It looks like most months I hover just under 400 KWH. Looking at the trendline, there’s an obvious spike in the winter months, with a tiny spike one month in summer when it’s unbearable without some AC. My hope this year is to reduce everything by 25%. I think it’s entirely doable, and using less light, less heat, and having my computer off more will go a long way towards that.

I’ve also been dabbling in energy generation. I built a stand for my bike so I can ride it indoors. Then I took a motor and attached it to the outer rim of the bike so that the spinning wheel would turn the motor and it would generate a current. I put a voltage regulator on it so that it would keep the voltage at +5 so that I wouldn’t blow out my cell phone, then hooked the wires up to a USB port so that it could charge my phone.

Surprisingly, this actually worked. Well, it was easy enough to generate electricity, and getting up to 5 volts was no problem at all, but my phone didn’t appear to be charging. So I sped up. And up. And up. I was cranking it as hard as I could in top gear before the charging light came on. I was also smelling ozone from the motor, so I decided to end the experiment. It was clearly not a sustainable solution, even though it did work for a few seconds.

So I thought the next approach would be to gear down so that I would have more resistance on the bike and it would spin the motor faster. The only set of gears I could find in my apartment were from an old CD player. I tried those and while I was still testing to see what kind of a current I could get I managed to put so much energy into the gears that they quickly melted and then broke. So that wasn’t going to work. Now I’m looking into buying used car alternators, which is probably the way I should have been going from the beginning. Still, it’s good to know that in a pinch I have the knowledge to generate electricity to power a small device.

Finally, I’m working on reducing my consumption in other areas. I’ll be even more vigilant about recycling everything, I’ll reuse things as I can, and I’m going to monitor how much trash I take out. I think that before I was taking out a single plastic grocery bag a week (I don’t buy garbage bags), which is pretty good, and I want to keep track of that to see how that continues. I’m also going to figure out a timer for my showers, and I’ll flush less frequently. That’s actually pretty hard because I’m so accustomed to lifting the seat, putting it down, and flushing that I often don’t realize until I’m washing my hands that I flushed when I shouldn’t have.

It is my hope that watching my consumption and taking small steps to reduce it will have a better effect on the environment and my pocketbook, without reducing my quality of life.

My Latest Mad Scientist Device

My friend Carolyn is getting an advanced degree through W.S.U Tri-Cities. One of the things she’s currently working on is a project that involves the use of an electric field to speed up bone regeneration. In the future, they hope to have biodegradable implants that could be placed at the site of a bone break that would create an electric current and help the bone grow faster. Right now they’re testing whether the current does have an effect on bone growth. Because of my ability with electronics, and my inability to say no to anything that sounds remotely cool, I ended up building the prototype testing device. I worked a lot with Carolyn to figure out what exactly she needed, and she was kind enough to order most of the parts and take care of getting me the materials I asked for. The electronics was up to me, though, and putting it together was my bag.

Essentially, the prototype has 12 ‘wells’ that will contain mouse bone cells immersed in a solution. They will be subjected to different currents for different durations. So I had to build something that would allow us to turn on and off the current to each well, and adjust the amount of electricity flowing through each well. The circuit is actually really simple, and the parts came from a variety of places. We’re even using straightened paper clips to dip into the solution.

It took me a lot of time to put it together. Well, one evening and one full day. But it looks great, and I’ve done a little bit of testing on it to make sure it’ll work. There are a couple extra features that will really help; the LEDs show which wells are turned on, and some pins on the side of the contraption will allow us to measure the voltage across the solution and the resistance of the solution.

I’m really excited about it, and pleased with my handiwork. It looks really slick from the top, and looking at it underneath makes a lot of sense and is pretty slick. Pretty much everything just seemed to work how I envisioned it. I did run into a couple snags along the way, but nothing I couldn’t handle.

I hope it will work for Carolyn. It’d be a shame to see it not used. Here are some pics of the device.