Category Archives: Hobbies

DreamSpark Plug

Microsoft DreamSparkWhat do you think about when you think of Microsoft? An evil corporate giant? Frustrating software? Viruses and worms? Or perhaps you’re actually a fan of M$?

Well regardless of your opinion, if you’re a student in high school or college, Microsoft wants to give you some of their software – free. Indeed, full versions of Windows Server 2008 R2, Visual Studio 2010 Professional, and more, are free to download with no strings attached. The program is called DreamSpark, and was announced over two years ago by Bill Gates himself during a speech at Stanford University. Somehow I didn’t catch word of this until just a few months ago when I started to look into building a new server.

So why am I mentioning this? Well, to be honest, I am a bit of a Microsoft fan. I’ve been using their operating systems and software ever since the arrival of the 486. But I’ve also now taken advantage of the DreamSpark program to download and install Windows Server 2008 R2 Standard (an OS that would normally set you back more than $500). In fact, it’s now hosting this blog (and playing a few other roles as well).

In the future I’ll probably comment on my experience with Windows Server, but for now I’ll just say the setup was pretty painless. I’ve toyed with Linux servers in the past, and configuring 2008 was, by comparison, approximately one million times easier. So, thank you Microsoft! (And please, Linux users, be nice to my new server. K? Thx!)

LabVIEW: Managing Interactive SubVIs

I do a lot of LabVIEW programming. Quite a lot, in fact. Fortunately, I rather enjoy a good block diagram. Plus, the ability to work with virtual instruments (VIs) for control and data acquisition seems highly prized at RPI. Either that, or nobody else wants to do it.

When building programs with LabVIEW, I often find it convenient to group code into subVIs. This can really help clean up a messy block diagram. Occasionally I’ll employ a subVI for user interaction of some type – a sophisticated dialog box, or perhaps a sub-application of sorts. But just how is this done? By default, a when you drag a subVI onto your block diagram, its front panel won’t show when executed. To force the front panel to display when called, first right-click on your subVI, then select “SubVI Node Setup.” Then simply check the following:

SubVI Node Setup

If checked, the option to “Close afterwards if originally closed” will close your subVI once it’s finished executing, if it started closed. This is typically my preference, but there may be a time when you want your subVI to stay open after it stops.

Of course, there are a few other tricks you may wish to employ. Perhaps you’d like your application to be reset its subVI’s values to defaults. Or maybe you’d like to run the subVI, but only display its front panel when certain conditions are true. All this and more is possible with the “Static VI Reference” block, found under “Programming” → “Application Control” and shown here:

Static VI Reference

Place this block on your diagram. Now drag your subVI onto the “Static VI Reference” block you’ve just created. You’ll notice it takes on the same icon as your subVI. From here there are a world of possibilities. To see what I mean, move your cursor over the reference output of this block (as if you were wiring it) and right-click. Next, select “Create” and then “Method for VI Class.”

VI Methods

From here, you can choose to run the subVI, show or hide its front panel, reset its values to default and more. If you back up a step on this menu tree and select “Property for VI Class,” you can further alter the appearance of the subVI window, including hiding buttons (abort, run, etc.) from the toolbar and changing the window title.

Hopefully you’ve found these tricks helpful! I’ll try to post more from time to time.

A Shiny Box of Fuel Cells

This week I completed the last of what RPI requires for a Master of Science degree in Electrical Engineering. Since I’d finished my thesis in the spring, I only needed three more credits to graduate. So I opted for a summer independent study. And what did I independently study? Fuel cells! (From an educator’s perspective.) It just so happened that my supervisor had previously purchased a commercial 300W PEM fuel cell stack. He wanted to use it in some sort of educational demonstration, but wasn’t sure exactly how to make that happen. So my project for the summer was to design and build just such a system. Our goals were to make the system:

  • Instructional for students of all ages
  • Portable and self-contained (no need to ever plug into AC power)
  • Visible (both the components and their connections)
  • Interactive (something you’d like to play with)

With this in mind I put together what I felt was a solid design, then went to work constructing it. With the help of some of my lab mates, we built the following:

Fuel Cell Demo System FrontWhat you see here is a large 80/20 box measuring about 30″ x 20″ x 11″ and covered with acrylic panels. As you probably guessed, the large red tank is the hydrogen supply, pressurized to 2000psi when full. That pressure is regulated down to about 6psi for the fuel cell stack. The gas passes through a ball flow meter and solenoid valve before reaching the fuel cell stack – located just to the left of and behind the red LED panel voltmeter.

Our fuel cell stack is produced by Horizon Fuel Cell Technologies, model H-300 (more details here). It’s an air-breathing PEM-type stack, composed of 72 individual fuel cells strung together in series. The voltage produced by the stack varies from 40-60VDC depending on the amount of current drawn. Now this variation is unsuitable for most electronics, so it’s first passed through a DC-DC converter (the largest black box just to the left of center). The converter takes the varying input voltage and steps it down to about 13VDC for use in the rest of the system.

You may also notice a 12V lead-acid battery strapped into the middle of the demo box. This serves two purposes. First, and most importantly, it provides power to the stack’s control module during startup. This is necessary to open the solenoid valve and engage the three fans mounted to the side of the stack. Second, it provides a bit of buffering during transients (e.g. when all the light bulbs are flipped on). One problem with fuel cells is that they cannot respond quickly to changing loads. Batteries, however, can rapidly supply more or less current without significant changes in voltage (large capacitors also have the same effect).

The rest of the system consists of an array of ten 12V, 13W light bulbs, a 120VAC inverter, and equipment to monitor voltages and current at several points within the system. This equipment is mounted to the rear of the system, shown here:

Fuel Cell Demo System Rear DAQ HardwareThe data acquisition (DAQ) module shown above is produced by National Instruments, model USB-6009, and is capable of monitoring eight analog inputs at 14-bit resolution. These analog inputs are fed from a custom PCB I designed, mounted directly below the DAQ module. This PCB is responsible for measuring currents using ACS712 hall-effect sensor ICs. It also performs voltage division so that the system’s voltages are within the measurement range of the DAQ. Last but not least, the PCB allows for computer control of the ten light bulbs using MOSFETs controlled by the DAQ’s digital outputs.

From the start, I knew I wanted to use LabVIEW to monitor and control the system – it’s built for data acquisition and handles simple controls quite well. The only question was, what sort of hardware should I run it with? Since I didn’t need much horesepower and in fact was looking to minimize electrical power consumption, I went with the Asus Eee PC, model 1001PX:

Asus Eee PC 1001PXWith its dual-core Atom processor, the 1001PX actually performs quite well running Windows XP. Its 20-30W power consumption (when charging) is equally impressive. Running LabVIEW 2009 presented no performance problems whatsoever. My only qualm is the lack of screen resolution – 1024 x 600 is just a bit tight most of the time. However, space was no issue since all of my LabVIEW VIs were compiled into executables without scrollbars, menubars, etc. Here’s how the main panel turned out:

LabVIEW Front Panel

From this panel the user can monitor voltage, current, and power at different points throughout the system. The light bulbs can be turned on and off with a single mouse click. I’ve also created VIs for taking polarization curves (voltage vs. current density) and for monitoring the stack’s voltage at high speed (48kHz) during transients. To top it all off, the Eee is loaded with a sample presentation containing the principles of operation for fuel cells as well as diagrams for the demo system itself.

The system has yet to be tested in a real classroom environment. Sadly, I may not be around to see that happen. But I’m pretty confident that it’ll be put to good use. The grand total for all parts in the system? About $4000. Thanks for reading!

Three Down, Forty-three to Go!

Last weekend I was back in the Adirondacks, hiking two more of the high peaks with a couple good friends. The weather was absolutely gorgeous – temperature no more than 60F, sunny, nearly unlimited visibility. We started out from the Adirondak Loj parking lot and headed south to Wright peak, elevation 4580 feet. As usual I brought along my Nikon D80 and all its paraphernalia. Here’s the view from Wright peak to the east (if I recall correctly):

Eastern View from Wright Peak

Looking the other direction, the peak of Algonquin still towered another 500 feet above us:

View of Algonquin from WrightWhile on Wright we had a quick lunch, then headed back to the trail for Algonquin. Again, the views were spectacular, and if anything the weather was even better. Here’s a panorama I stitched together with Microsoft Image Composition Editor (the peak just to the right of center is Colden, my very first):

Panorama from Algonquin
That 37.6-megapixel composite came from eight separate shots taken over about 200 degrees. I must say, ICE is a pretty impressive program. All you do is open it up, feed it a batch of images, and away it goes. I’ve been using it for a number of months now and it’s performed exceptionally fast and its stitching is accurate. It definitely tops Auto-stitch, which I used previously.

Our sum total for the day: eight miles, seven hours, 3000′ elevation gain, and so much fun. So for me, three high peaks down, another forty-three to go! 🙂

For a list of all the high peaks in the Adirondacks, try: http://www.adk46r.org/listf.html.