Some of us might solve crossword puzzles or Sudoko games to exercise our minds, but [Nathan Nichols] plays with exotic number systems to keep the brain cells in shape. He wrote the Hanoi C99 library while in high school, implementing several of his favorites.
We have all been using decimal (base 10) and duodecimal (base 12, as in clocks) since before grade school. Us computer geeks are also adept at various computer-friendly systems like binary, octal, and hexadecimal. The true nerds among us will be familiar with systems like vigesimal (base 20 Mayan numerals) and sexagesimal (base 60 Babylonian numbers). We ourselves espoused the virtues of seximal (base 6) a couple of years ago. But if you really want to stretch your mind, take a dive into the weird number systems that [Nathan] has been exploring.
A number is represented by its path down the Stern-Brocot tree. One feature of this system is that numbers can be exact. For example, the Stern-Brocot tree representation of one-third has a finite number of digits.
While [Nathan]’s library only performs conversion at input or output, we wonder if someone will take this further and implement an arithmetic unit inside an FPGA. Besides being a fun exercise, it would baffle someone casually trying to reverse engineer your secret calculations. Let us know of any strange number systems you have used or encountered.
We bet you have all some cool part in your bin that is just gnawing at you to build something cool. That doodad, possibly from a garage sale, surplus store, or clearance rack deserves a project fitting of its near-infinite potential. [isaac879] finally marries a giant ball bearing with his passion for photography in the form of a pan-tilt camera mount for his Canon DSLR. The problem with tossing your golden-ticket part into a project is that not everyone has a MacGuffin, or a brand new one might be bank-breakingly expensive, so he does us a favor and makes a drop-in replacement that you can print and fill with 6mm brass bbs. This sort of thing is why we love hackers.
The camera mount has the features we expect to see in a robust stepper mount, such as infinite spinning, time delay, and an Xbox controller interface. Inside the base is the industrial bearing or its plastic replica, and that wide base won’t be tipping over anytime soon. Gearing all around is of the herringbone style, of the type you find in classroom pencil sharpeners because they transfer power smoothly. Speaking of things going smoothly, we enjoyed his assembly montage where every part fits together perfectly and there is not a naughty word to be uttered. Just like real life.
The 1970’s was the decade that illuminated the threat of acid rain to the citizens of the US. It had been known to exist several years before, but the sources of the problem did their best to suppress the information. It wasn’t until the environmental damage became significant enough to draw national attention that it would lead to the US enacting regulations to stop acid rain.
Truthfully, most of the public was probably still unaware of what acid rain actually was. The default mental image that comes to the mind of the non-chemist is large drops of battery acid raining down from the heavens and devouring everything. This is not quite the case, however. Pure water has a neutral pH of 7. Normal rain is actually slightly acidic as it picks up CO2 from the air, making carbonic acid. But when this “normal” rain mixes with the byproducts of industrial plants that pump out large amounts of SO2 (sulfuric dioxide) and NO (nitrogen oxide) into the atmosphere, it becomes even more acidic – down to a pH of 3. This “acid” rain has the acidity of citrus juice, so it’s not going to set the world on fire. But it will wreak havoc on local ecosystems.
The 1990’s brought with it tough government regulations on the output of SO2 and NO by large factories, pretty much eliminating acid rain in the US. The rise and fall of acid rain is a great example of why we should educate ourselves on the basic chemistries that define our lives, even though we might not be actual chemists. In this article, we’re going back to your first year of college and hash out just what defines an acid and base. And solidify our understanding of the pH scale. It is essential for the future biohacker to have this knowledge in their toolbox.
Nearly everything at [HAD] is at least based on science in some way or another. If, however, you would like to do some actual scientific experiments with stuff around the house, [Observationsblog] might be for you.
The particular posts that [Ken] wrote in to tell us about were all about acids, bases, and natural indicators. In his first post he goes over some definitions of acids, bases, and what pH exactly means. A good refresher for those that have forgotten some of their high school (or college) chemistry classes.
The other two posts have to do with making your own natural acid/base indicators. The first is called Anthocyanin, and can be extracted from Red Cabbage. Quite specific directions can be found here. Similar directions can be found to turn the Indian spice of [Turmeric] into an indicator as well. Although these concepts probably won’t help build your next robot, they could easily be copied inspire young minds for a great science fair project!
[Matt] brought together a TV remote and cordless phone to add a locator system to the remote control. One of the best features of a cordless phone is the pager button on the base. When you press it the handset beeps until found. Matt gutted one and got rid of the unnecessary parts. He then cracked open his TV remote housing and inserted the telephone handset’s circuit board, speaker, and battery. The base station is used just like normal to locate the phone/remote combo, and has been modified with a charging cable to top-off the telephone battery which powers everything in the newly hacked unit. [Matt’s] demonstration video is embedded after the break.
It’s too bad that he got rid of the microphone. It would be interesting to take calls on this thing.
[Milapse] picked up a motorized telescope base a few years ago. He’s using it to add motion to time-lapse photography. The base provides two-axis rotation controlled with a handheld keypad. Custom firmware and a bit of software allow for computer control. [Milapse] is pretty well-known in the time-lapse photography circles of the Inter-web. He’s posted a ten minute video explaining his setup and programming work for the hardware.
This is a great example of how marketing should be done. TeleToyland and RoboRealm(currently down) have teamed up together to show you how to build a quick and easy robot base for your netbook. The build process is fairly in depth, including part numbers and links to various places to buy them. They are using RoboRealm software to control the robot, utilizing two web cams for sensory input. This should get you well on your way to having an autonomous netbook wandering around your house.