Tuesday, December 20, 2011

Learning to surf in Barbados

Surfing has always been an activity I've wanted to try in my adult life.  A major stumbling block in this endeavor, up to now, has been opportunity.  Unlike skiing, surfing isn't something the novice generally designs a vacation around.  At least I've never thought about it.  I live reasonably close to the Delaware and Maryland Beaches but body surfing and sun soaking has always been the name of the game out there. That and I have yet to witness people getting any sort of instruction on the beach. Trust me, a good lesson is key.

Deb and I took a trip out to Barbados recently to visit a friend and stumbled upon a little free time during our last day there. Actually we had the whole day to ourselves and I pushed for surfing lessons pretty hard.  My wife was quite nervous about the idea partly because she didn't know whether she could do it or not. I'll give you one guess who the better surfer turned out to be.  It must be because she's shorter. By the way, this video is pretty much all you need to know about Barbados.  Remember what I told you about a good lesson. Well, the instructor is a big part of that. I can't imagine a better guide than Jonathan (Jona) from Barry's Surf Barbados Surf School.  He had us up on the board almost immediately.  It was apparent after watching other instructors on the beach that we lucked out.

I picked this video because I think it best captures the proper technique to successfully stand up on a long board.  That and it's the only video I had. The hardest part for me was remembering to look up toward the beach.  Your tendency is the check out your feet placement after standing up but that will almost assuredly put you in the ocean. I'm a little wobbly there at the end but to my defense, it was my third time out that day and the sea was rough my friends. Well, rough for a land lover. Definitely something everyone should try at least once.

Wednesday, October 19, 2011

My first foray into the modern cooking movement

Holding steady at 140° F
I started cooking a lot more when I met my wife. And by that I mean I helped her when she cooked. I was still a relative novice but wanted to learn. The really tricky part was figuring out where to start. We realized early on that our styles where quite different which led to a few clashes in the kitchen.  Mostly because I asked way too many questions. Deb cooks more on taste and feel and I want to know what's going on under the hood. I discovered a book called Cooking for Geeks which, as you can probably tell, spoke to me immediately. It dives into the chemistry and physics of cooking right away and delivers it in an easily understood manner. I was particularly enthralled with the chapter on Sous Vide cooking. Not only was the science noteworthy but the hardware involved was also of particular interest to me. Unfortunately the cheapest commercially available unit costs in the range of $400. Okay, I was gonna build one before I even knew the price tag.

Sous Vide, pronounced "Sue Veed", is a way of cooking food by submerging it in a very accurate temperature controlled water bath. The food is vacuum sealed in a plastic bag to keep the water out and keep the moisture and aromas in. This method eliminates any chance of overcooking the meal and ensures that it is heated evenly throughout.  You get a perfectly done steak or piece of fish every time. More about that later though.

With pretty much all of my projects, I like to start off by scouring the internet to get a good idea of what's already out there. I found this little gem on Make and figured it was a great place to begin. The design revolves around a PID controller which continually reads in the water bath temperature with a k type thermocouple and cycles three heating elements either on or off based on the current temperature, rate of temperature change and distance from desired temperature.  Normally it would be a lot cooler if I made my own controller but for $30, it was hard to beat the off the shelf unit they spec'd.

Sheet Metal Work
I was't a fan of the enclosure they used so I leveraged my meager metal working skills and made my own.  Making cut outs in 1/8" aluminum is not fun. After cutting a series of smaller holes on the drill press, I filed down the inner edges to make them flat and smooth. To make the box, I bent all the side walls toward each other and used epoxy where they met on the inside to secure them in place. More grinding was necessary to round off the joints.  This was the most time consuming portion of the project. Took a few iterations of sanding and priming to get the edges just right.  I was quite please with how they turned out.  Like the paint job?  Gotta thank my pal Tommy S. for the inspiration. How better to paint a slow cooker than with racing stripes. Check out the nod to the French racing blue Renault Clio 182.

I think it's time to talk performance and results. The controller and associated thermocouple kept the water bath temperature within two tenths of a degree of the set temp.  That's more than accurate enough for the purpose of this machine. And when heating up room temp water, it can add enough energy to increase the temp of about two gallons of water approximately 2°F per minute. That's not great but considering the water coming out of the tap can reach about 130°F, you really don't have to wait too long.

Perfect medium rare steak
I decided to start the real testing with something easy, a couple of 5oz filet mignon steaks. Flanked the meal with some roasted yukon golds and sauteed broccoli. I set the immersion cooker at 140°F, vacuum sealed up the meat (covered in a little garlic, thyme, olive oil, salt and pepper) and let it cook  for an hour and fifteen minutes. As a result of cooking at a relatively low temperature, the browning reactions normally associated with a steak will not take place. This is easily overcome with some quick searing action on a smoking hot cast iron skillet. Around 45 seconds a side should do it. As you can see in the picture above, the steak is cooked evenly throughout. I also verified with a thermometer that the meat was a perfect 140°F. A little moisture was left over in the bag but not enough to really matter. The resultant steak was extremely tender and juicy.  

The obvious drawback to this style of cooking is the long cook times necessary to neutralize any bacteria present in the food. Bacteria will die within minutes at 160°F but it takes considerable longer at lower temperatures. There are many guides available to aide you with these calculations. I don't mind the long lead.  My thinking is, where's the fire baby? Life is to be simmered and enjoyed.  Sous Vide isn't for every meal but it does add another interesting preparation option in the kitchen and a good one at that. I'm looking forward to further experimentation and more delicious food.

Tuesday, August 30, 2011

Watermelon Gin Jalapeno Limeade Spritzer

On a trip out to Cosi a little while back, I sampled their Watermelon Habanero Lemonade and was thoroughly impressed.  Sweet, spicy and very refreshing.  I really needed to make this into a cocktail. On a recent sunny Sunday afternoon I sequestered myself in the kitchen endeavoring to do just that. I was going to start with store bought lemonade but my wife suggested that I take a look at Emeril's Watermelon Limeade recipe before I do.  Always with a good idea up her sleeve, I listened and whipped up a batch.  Start with 8 cups of loosely packed watermelon (seeds removed) and blend until liquefied. Strain until all the pulp is removed. You should be left with about a quart (4 cups) of juice.  Add one cup of fresh lime juice along with a half cup of sugar and you're done.  This in itself is very tasty but it's not a cocktail just yet.  Cosi used Habanero peppers in it's drink but I'm a huge fan of Jalapenos so I went that route. Cut the peppers in half lengthwise and scrape all the seeds and pulp out with a spoon. That's where most of the heat is and I'm looking for taste not bite.  Slice the pepper into 1/8" pieces and set aside.  A little pepper goes a long way so when building your drink, start with about 4 half moon slices and add to taste. I associate Gin with summertime cocktails so that was a no brainer. I prefer Hendricks but that can be a bit pricey so Beefeater is just fine. To finish things off I added an equal amount of Club Soda for that carbonated kick.  Tasty drink and fun to make. Though I think I need a better name. Suggestions?

Watermelon Gin Jalapeno Limeade Spritzer
     - 1 oz. Gin
     - 1 oz. Club Soda
     - 5 oz. Watermelon Limeade
     - 4 slices Jalapeno halves (1/8" thick, seeds and pulp removed)

Add Gin, Club Soda and Jalapeno to rocks glass, let sit for about a minute.  Add ice till about 3/4 full.  Top with Watermelon Limeade and stir. Enjoy!

Monday, August 15, 2011

Undercounter iPad dock

My wife and I own many cookbooks but more often than not we look to the interwebs for recipes. I got my wife an iPad for her birthday when I finally got tired of scrolling through verbose assembly instructions on an iPhone. Prior to purchasing the wonder tablet I knew that our lack of counter space left few options for placing the iPad out of the way yet accessible at the same time. I would have to go vertical.

At first I thought about modifying a COTS (consumer off the shelf) iPad case and mounting it to the face of a cabinet but I didn't feel comfortable swinging the thing around every time we wanted to get a plate.  After hitting a slight creative block, I was inspired by a couple drawer slides I found whilst fumbling around my spare parts box. I could mount the dock to the underside of a cabinet and slide it out and over the sink when it's needed. However, in this configuration, I would only have 1 and 1/8 inches of clearance to work with. Subtracting the width of the iPad (1/2"), the iPad holder (1/4") and the logically minimal width of a sturdy base (1/4")... I was running out of room quickly.  I would have to lay the iPad holder flat against the base and somehow conjure up enough space to fashion some sort of kickstand mechanism.

Knowing that I had no height to work with, I envisioned an opening in the base where the hinged portion of the dock would reside.  I also thought up notches in that opening that would later accept a couple of saw tooth sections to act as adjustable stops for a kickstand. Luckily I have access to a laser cutting table. Otherwise, cutting out the design below would have been impossible with a Dremel.

Figure 1: CAD drawing for laser cutting table
The kickstand affixes to the underside of the hinged section with a couple of brackets that were also cut out using the drawing in Figure 1. Love that laser. I made the kickstand by bending up a piece of 1/8" tubular aluminum on a vice. There was as little trial and error involved here. I had to get the leg sections the exact same length or else they wouldn't sit on the stops properly. I wouldn't want the iPad to wobble around now would I.

I made the iPad holder out of 1/16" sheet aluminum which I painted a shiny black with a couple coats of clear acrylic for protection.  This is also the case where having the right tools really makes the job easy. Having a good sheet metal cutter and bender makes all the difference. I left a little slack around the iPad to put a thin felt pad to minimize scratching but turns out the current finish is soft enough and any additional material may not be necessary.

There are a couple things I would have done differently had I owned the house. First off, building the drawer slides into the cabinet so it's totally hidden when not in use would have been really neat.  I'll shelf that idea until I put up some custom cabinets of my own.  Next, having the whole thing motorized would bring this to the next level. Completely unnecessary but cool none the less.  I had that notion from the very beginning so I designed it with that potential upgrade in mind. Though I have many more projects in mind so that will have to wait for another day.

Monday, June 27, 2011

Fun with sensors

A couple years ago I put together a kegerator and while draft beer at home is great, the project never felt complete. The system performed well but there were a couple of issues that would crop up from time to time. Mainly, figuring out how much beer was left in the fridge consisted of opening the door and pawing at the keg.  Besides this being unscientific, the act of opening the door would let all the cold air out and the compressor would have to crank to keep up. And speaking of temperature, it would be nice to have a good idea of how cold the keg is getting.

Scale for Fuel Gauge Measurement
Incorporating a temperature sensor was obvious. Though there are many different types so choosing wasn't easy. We'll get to that later. To make a beer fuel gauge I decided to tag team a couple different sensors to make as accurate a reading as possible. First I constructed a crude scale to house a couple force sensors I got from Sparkfun. To supplement the weight measurement, I added a Swiss Flow SF800 flow rate meter to the mix. You can never have too many sensors. I ended up not needing the flow meter for the fuel gauge but it got used when I wanted to know when beer was flowing or not. You'll see why that's important in the video below. I was reluctant to include the flow meter initially because I thought there was a chance if would disrupt the flow of beer and create more foam than usual. While this is the case, it wasn't significant enough to remove it.

I thought the temp sensor was a no-brainer but it turned out to be a little tricky. Idealy, I'd like to know the actual temp of the beer but since the keg is a sealed container, that is impossible. The next best thing would have been to simulate the keg with an approximate thermal mass and sense the temperature of that but I didn't have the space.  That and I had already decided to be lazy and use a board mounted digital temperature sensor instead. Couple drawbacks with that idea though.  Since it is soldered to the sensor control board, thermal coupling to said board is an issue and placement in the fridge cavity is somewhat limited.  And to get a reading that actually means something, placement is critical. Turns out that placing the board right under the fridge chill plate gave me some pretty accurate results when compared to a mercury thermometer. And it was a good indication of what the fridge's themocouple was reading since the compressor cycle and my temperature readings tracked almost exactly in phase. That's important because one day I may want to take over control of that cycle for tighter temperature regulation.

So now I want to display all the good data I'm getting.  I used cast iron pipe for my keg riser so I felt it was necessary to stick to that theme and go a little industrial with my display options. After an exhaustive search online, I finally came across the perfect meter housing from an early model Chevy. On ebay of course.  It was pretty beat up when I first got it with splotchy paint and some pretty rough edges. I was originally going to sand and paint the thing but ended up trying my hand at paint stripping instead. Peep the before and after.

Meter Housing Before and After
I'm gonna have to give credit to CitriStrip on this one.  It made short work of that old paint.  A little grinding here and polishing there and... well, I still had an empty shell.  That is until I modified up a couple analog meters to stick in there. 

Modified  0-5 Volt Analog Meter
They were a little small but hey, when life gives you a little space fill it up with light from an RGB LED I say. What would one of my projects be if I didn't throw some lumens at it. You'll want to check out the video for full effect.

I made four boards for this project. They are mostly unpopulated in the picture to the left because I like to test out the micro first before I finish them up. I'm weird that way. The board at the bottom went in the keg fridge and has circuitry to read all the sensors. It also manipulates the data into an easily read format for the display control board in the middle. That board drives the Tri-Color LED drivers and does a couple D/A conversion to drive the analog meters. The board on the upper left will eventually house a relay to control the compressor cycle and the board right next to that is a RS232 level shifter so I can divert the TTL level UART signal intended for the display board to a PC for debug purposes. Being able to save the sensor data off to a PC was also helpful when developing my display averaging algorithms.   

I never thought my kegerator was stupid before but it sure is smart now. If only if would help me brew beer too. I guess that's the next step.

Wednesday, May 25, 2011

Custom picture frames are expensive

I bought a 20 dollar world map a while ago and never got around to framing it until recently. The map is approximately 45" by 30" so it's safe to say that an off the shelf frame isn't going to do the trick. There are a couple custom framing shops around town but I knew Michaels had an extensive framing department and with my 55% off custom framing coupon firmly in hand I rolled out to one of my favorite stores confident I could grab up a sweet frame and not break the bank. And since the map was already laminated with it's own border I could forgo the matting and glass/plexi to save some dough. I truly thought I could step out of the store minus somewhere in the vicinity of 75 to 100 dollars. And yikes! I was way off. Even after the coupon, the least expensive option was about $250. I think it's safe to say I didn't buy a frame that day.  And $250 was pretty bare bones. You're not getting a fancy wood stain or two tone metal frame for that. Michaels, I still love ya but I'd have to pursue other options for my framing needs.  What was I going to do?

Let me start by saying that my wood working skills are minimal at best. I am aware of the necessary tools but own few of them. I had the cordless drill and screwdriver, needed to borrow the miter saw and router from a neighbor and had to buy a couple right angle clamps.  The clamps were only a few bucks at home depot and totally critical if you want to properly align the segments as seen in the picture to the left.  I also borrowed a router bit (1/2" rabbet) from work which was key because those suckers can be expensive.

You can find all the materials necessary to build this frame at Home Depot. I went with a 1x3" maple board for it's attractive grain pattern and light color. The color makes a difference when deciding on the stain color that suits you. I chose Minwax Red Mahogany 225 because it looked great and would be a close match to the furniture already in the room. You'll want to test the stain on a scrap piece of wood to make sure the color is what you want. For the protective coating, I went with a Minwax Semi-Gloss Polyurethane. I thought the gloss poly was a bit too reflective for my taste. I already had the wood glue, filler, sandpaper and assorted screws from a previous project but all can be purchased for under 10 dollars.

Before you start cutting, identify the portions of wood you want to face the outside world. And kids, remember the golden rule in woodwork...well, construction in general. Measure twice, cut once. Getting the measurements right when cutting and matching up 45 degree angles can be tricky so take your time. Don't worry if they aren't perfect, mine weren't.  This is where the wood filler comes in. A little goes a long way.  Check out the picture, looks dead on doesn't it. After you have glued screwed and clamped the four corners, apply the filler where needed and let dry. The frame actually looks pretty good at this point but looks even better when you hit the whole thing with some 220 grit sandpaper. Be sure to go with the grain and be careful around the joints. At this point the initial plan was to just tack the backer board to the rear of the frame but I decided to route out an 8th inch deep half inch rabbet instead to inlay the backer. Looks more professional from the front this way. BTW, had one of the guys at the Depot cut the backer for me. Saved me a bunch of time and trouble.  If I ever make a frame again, doing the routing before assembling the parts is totally the way to go.  I ended up having to freehand it.  The result was far from perfect but it's the back of the frame so no one will see it.

When it comes to applying the stain, follow the instructions on the can and you'll be just fine. I do have a couple tips though. I prefer foam brushes over rags. They are cheep, you can use them for multiple coats and they do a better job of getting into corners.  And mineral spirits between coats of stain and polyurethane are essential. Dust is not your friend in this situation. Use a sandpaper in the high 200 grit between coats of stain and something like 320 before the last coat of poly. That will give you the nice glass like finish you're lookin for. All that's left after that is to glue on the backer and tack on some wall mounting hardware and you're done.

We have some other picture frames in the room from Crate and Barrel that have a similar style so this fits right in. I could have used the router to round off the edges or cut some sort of decoration into the wood but thought something simple and understated was appropriate considering the look of the map it was framing.

The basement smelled like stain for a few days but that was worth it when I think about the couple hundred dollars I saved in the process. The overall cost came in at a little under $40. Take that Michaels!

Thursday, March 24, 2011

Always drink to world peace

I've been gearing up to brew some beer at home for some time now, so when Maz and White Noise asked if I wanted to make a batch at Shenandoah Brewing Company I decided to join in figuring it'd be a good place to ask some questions. Indeed it was. SBC provides everything you need and takes you through the whole process from deciding on a recipe to bottling.  They must have a few dozen different varieties to choose from. They range from ales to lagers to hefeweizens and they'll gladly work with ya if there's something you'd like to experiment with. We decided on a India Pale Ale (IPA) made primarily with Centennial Hops. I don't have much information about that particular strain of hops other than it hails from the pacific NW and it's popular as well as tasty.  As you can probably infer from our label, we brewed this IPA on Groundhogs Day.  Boy, that hog sure is dramatic.  Took a bit of photoshopping, but I think the labels came together nicely. I Lifted the "Gobbler's Knob" right off a picture of the actual Punxsy Phil sign.

The brewing was pretty straight forward. The only part of the process that was prepared for us was the wort.  Wort contains the sugars that will later be fermented to make the all important alcohol content of the beer.  As I understand it, wort is made by steeping a mixture of ground up malted barley and grain adjuncts. The steeping creates an environment favorable for enzymes to convert starches into sugars. Apparently to make home brewing easier, malted barley extracts can be added to the grain tea mixture in lue of embarking on the malting process yourself. Good to know.

We started off by precisely weighing each stage of hops and gathering them into bowls. We took the bowls over to the kettle where the next hour or so of boiling would take place.  The wort is added to the boiling water first followed by the various stages of hops at predetermined intervals.  Boiling the wort accomplishes a few things.  It sterilizes the mixture, coagulates proteins and stop enzyme action.  Basically kills all the stuff living in the wort while extracting the desired color and flavor. The hops are added in intervals to balance out the taste and aromas.  Resins in the hops are broken down slowly and add bitterness to the taste while the oils from the hops evaporate quickly and add aromas. Adding the hops had to be done slowly because they threatened to boil over if done without care. A little bit of kettle tech came in very handy here. Instead of having a single heating element at the bottom, steam is funneled into jackets surrounding the kettle to add energy more evenly which gives you fine control over the temp of the kettle contents. There was no problem backing off the heat at any point because you can regain your previous temp very quickly. After the boiling is complete, the liquid is filtered and run through a heat exchanger where the temp is lowered to a point that is not hazardous to yeast cultures. We added a packet of yeast and rolled the plastic keg around on the floor for a bit to oxygenate the mixture.  Around 6 weeks later, we came back to bottle up our creation and take a taste test. The yeast gobbling up all the sugar will create a little carbon dioxide but a little more was added to give it that extra carbonated kick.  It was recommended that we store the beer in a dark place for at least two weeks before cracking one open. This gives the beer a chance to settle down and balance out after being carbonated.

Turned out to be a pretty typical IPA. Crisp and hoppy but not overly bitter. It's gonna be nice to drink on a warm spring day. The one major takeaway from this experience is that the world of beer brewing is immense. There are just about a million factors that go into the taste, smell, alcohol content and look of a beer. The hardness of the water, temp of brewing, species of yeast, type of hops, variety of grain adjuncts, process of malting, and a host of other factors all really matter. Kind of intimidating at first glance. Don't think that's gonna stop me though. I'll most likely try to recreate the Knob at home with my own equipment and see how that goes. Can't wait to blog about that.

Thursday, February 24, 2011

Monkeying Around

My neighbor throws a pretty mean jungle themed party every year and I like to participate whenever possible.  Which is pretty much every year since this party is not to be missed.  I've wanted to go ape for a couple years now but didn't have the tools til recently. I could have bought or rented but it's kinda of expensive and what would I have learned?

Having a sewing machine is key when putting together a large costume. It made short work of the long seams necessary in what turned out to be a basic jumpsuit made out of fake fur. I got a vintage '70s pattern from ebay for around 3 bucks and the fabric from Jo-Ann Fabrics for less than $30.  Where would my hobbies be without ebay? The picture on the left is a part realization of the initial concept which involved the ape suit and my wife dressing as Jane Goodall.  The trucker hat would have said something like "I'm with Goodall".  We scrapped the Goodall portion but I made the trucker hat anyway. I went with something slightly vulgar for the hat epigram to fit the anticipated party atmosphere.  I borrowed the mask from my friend Otto for the few minutes during the party.  Good thing too, the costume/mask combo got quite hot.  I could never be a real gorilla. 

I learned a few things about following patterns and judging size and fit but I still have a way to go if I want to put together a more form fitting ensemble.  I'll just have to keep on practicing.  It's a good thing I have plenty of time before the next Santa suit bar crawl.  The wheels have already begun turning on that getup.

Wednesday, January 05, 2011


Making fun little lighting projects is just one of my hobbies.  Interjecting my unsolicited opinion on the design of other people's projects is another.  My neighbors embarked on a basement remodel a while back and, like a moth to a light bulb, I fluttered about living vicariously through their ambitions.  I'm pretty sure doing something similar or anything more than hanging a well framed painting on the wall of my rented townhouse is some sort of lease violation. I said, "those are some nice shelves".  They said, "thanks".  I said, "you know what would look cool".  They said, "do it".  They have obviously read my blog.

The shelves are 16" cubed, built into the wall, made out of sheet rock and painted white.  I wanted to light'em up and I knew just what to do.  The trick was finding a RGB LED worthy of the job.  DealExtreme is a tad sketchy and based out of China but pretty much my only bet for 3W RGB's at anything close to a reasonable price.

The construction of the circuit board was pretty straight forward with only one notable addition.  Along with the 3.3V power supply, LED driver chips (CAT4103), and obligatory PIC micro-controller (PIC18F2510), I used a Lantronix XPORT Ethernet to Serial module to accept commands from any network attached device.  It was agreed that I would leave all the software design up to the neighbors.  After all, they are the professionals.  My board reads in a command packet, writes the LED intensity registers and creates a pulse width modulated (PWM) signal to update the RGB LED drivers.  When I design any board, I like to make it as versatile as possible in the event I decide to add any features after the fact.  There are only 7 shelves but I built the board with 12 drivers just in case.  Two boards can also be stacked to drive a total of 24 RGB LED's as you can see in the picture below.  Turns out we'd need all 24 but I'll tell you more about that later.

So I finished the hardware, installed my custom firmware and performed the least amount of testing it took to convince myself that there was a chance it could work.  My neighbor Mark was designing his visualization software in parallel with only a loose discussion of what the command packet should look like to go by.  The idea was to get together once each part was done and spend way too much time debugging the inevitable problems. That is until it worked right out of the gate.  Sometimes the lighting of a single indicator LED can stir up a bevy of emotions in the average geek... imagine the lighting of an entire bank of shelves.  I'll have to admit, Mark's software is pretty impressive. My favorite part is the connection with iTunes.  While a song is playing, it gathers frequency information on the fly and displays it on the shelves in a variety of ways. Check out the video at the bottom to get a better idea of what I'm talking about.

If working solo, I may have called it a project and moved on.  However, the neighbors had a vision and a suspicion that I wouldn't leave them hanging.  They installed 20 overhead can lights in the drop ceiling and four wall sconces in the theater section.  24 extra LED's huh, yikes!

The hardware wasn't a big deal cause it was pretty much done already.  LED installation and firmware development... Now that was a bit tricky. The room lighting was already wired up for 120Vac so the LED's had to be installed in such a way that proper light diffusion was achieved within the housing and the housing itself wasn't altered in a severe way.  The blue socket protection cap provided as close to a perfect solution as we were going to get. The cap was meant to fit snugly into the existing light socket so I just mounted the LED to that and attached a strain relief on the side. Neat and tidy.

So for the ceiling and walls, that is 24 RGB LED's which makes 72 (24x3) discrete sources of light.  To drive each LED at different intensity levels, I switch them on an off at a set frequency and vary the percent at which each LED is on during a cycle period.  If it's on half the time, it appears to be half as bright as a LED that is continually shining.  For this project I chose a refresh frequency of 60Hz with 32 levels of intensity.  Therefore, I have to update each of the 72 LED's 32 times every 1/60th of a second.  In other words, I have 520 microseconds to update 72 LED's.  With a 16MHz oscillator, the instruction cycle on my micro-controller is 250nS. So, the update period divided by the instruction cycle time divided by the number of LEDs gives me a total of 26 instructions to preform everything needed to decide whether a given LED needs to be on or off.   I ended up needing 22.  Just squeaked it in there after a bunch of tweaking and a little luck. 

The shelves and ceiling have a refresh rate of 30Hz and can generate over 30 thousand colors per pixel.  A pixel is a single shelf or can light in this case.  Not bad for a few bucks and hours of spare time. Best part, Both the shelves and ceiling consume less than 50 Watts when fully lit. And less than 10 on average when in visualization mode.  That's around the power draw of an incandescent night light.  Saving the planet one disco basement at a time.

I'm pretty psyched about this install.   I mean, it's what I'm really passionate about and, if I could toot my own horn for second, I may actually be getting kind of good at it.  What do you think?

Here are more videos for your viewing pleasure.  Thanks Mark.