Generating truly random sequences

Your brain can’t generate random numbers, and computers can’t either. Most of the ‘random’ numbers we come across in our lives are actually pseudorandom numbers; random enough for their purpose, but ordered enough to throw statistical analyses for a loop. [Giorgio] thought generating random sequences would make for an excellent project, so he whipped up a random sequence generator out of a few Opamps, resistors, and a handful of caps.

[Giorgio] used a Chua Circuit – a circuit that models nonlinear equations – to create a chaotic system. When pairs of points from these systems of equations are plotted on a graph, a fabulous and chaotic ‘double scroll’ pattern (seen above) can be found. After taking oscilloscope probes to different points on his Chua circuit, [Giorgio] watched chaos magically appear on his ‘oscope screen.

The double scroll pattern isn’t exactly random, but since the Z signal of his circuit chaotically varies between positive and negative, the only thing needed to create a random sequence of 1s and 0s is sending the Z signal through a comparator.

After calibrating and sampling his circuit [Giorgio] captured thousands of samples at a rate of 5 samples per second. From a cursory glance, it looks like [Giorgio]‘s circuit is at least as good as flipping a coin, but proper tests for randomness require many more samples.

A very, very cool piece of work that is much, much more elegant than getting random bits from a Geiger counter.

USB business card packs an ARM processor

Over on the Hackaday forums, [Brian] introduced himself by showing off his new business card. Given his expertise is creating unique circuit boards, we can’t imagine a better way to show off his skills than an ARM-powered business card.

[Brian] posted a more detailed write-up on his blog that covers his development process. He decided to use a 48-pin LPC1343 ARM Cortex M3 as a USB Mass Storage Class device. All the heavy lifting for instantiating a USB storage device is handled by the microcontroller, so all [Brian] had to do was wire up a Flash memory chip and access it over an SPI interface.

The finished business card functions just like a USB thumb drive with a whopping 1 Megabyte of storage. That’s not a lot of storage, but it has more than enough room for [Brian]‘s resume, a link to his website, and the full source code for his card.

Should we make games for fish?

I have often sat, gazing at my aquarium, wondering what life is like for those critters I keep captive. Are they bored and yearning to be set free? Are they content with their gluttonous lifestyle and constant pampering?

This is a question that is often raised with animals of a higher order, like pachyderm in the zoo, or chimpanzee. Those are easier to personify and to debate, but those are also, not often in our homes.

I keep my aquariums overgrown with actual live plant life. I have a flourishing ecosystem of natural plant filtration and invertebrates that I truly enjoy watching as they pick at the debris and bustle throughout the day. I test my water regularly to make sure it is optimal for the health of all involved. But my fish, well, as I said, I wonder about them.

[Read more...]

Uncovering easter eggs in old Mac ROMs

The picture you see above is taken from the ROM of a Macintosh SE made in the  late 1980s. This black and white image remained buried inside old Macs until [Adam] and [Trammell] at NYC Resistor reverse engineered these old Mac ROMs and found a few really cool Easter eggs.

[Adam] and [Trammell] have been dumping ROMs from old computers for a while now. Their modus operandi is finding old 27C-series EPROMs on old computers, prying the out of their comfortable home, slapping them in a breadboard, and wiring up an Arduino clone to dump the data to a computer.

Recently, the guys found an old Mac SE lying on the side of a road in Brooklyn and brought it over to NYC Resistor. They had known about images hidden in the SE ROM, but the guys wanted to know how and where these pictures were stored. After carefully inspecting the binary file generated from dumping the ROM, [Adam] was able to recover three images hidden in every Macintosh SE.

The folks at Apple – especially in the heady days of the Apple II and 68k Macs – hid quite a few Easter eggs in the ROMs of their computers. For instance, the Apple IIgs has audio data stored in the ROM, and the Macintosh Classic hid an entire operating system – System 6.0.3 – in the ROM of the machine.

via Make

Hackerspace grand opening tonight in Portsmouth NH

The Port City hackerspace will be opening its doors tonight at 7pm for their grand opening party.  Judging from the pictures on their site, they’ve actually had the space long enough to get the tools set up and even do a few projects. This should be a good way to jump start the membership though.  Like most hackerspaces should, they are offering classes to people to educate them on the use of the tools and proper safety.

They have the usual full shop, but they also have a designated bike shop, where they will have several custom bikes on display. If you’re in the area, you should be sure to swing by and check it out. You are assured to at least get some delicious bar-b-que out of the deal.

Volt meter clock also displays the temperature

[IronJungle] got around to putting together every tinkerers favorite project: a clock with a strange way of displaying the time. For his clock, [Jungle] took a trio of voltmeters and turned them into a clock that displays the current hour, minute, and second on custom paper dials.

[IronJungle] connected a PIC 14M2 microcontroller to a DS1307 real time clock to keep track of the current time. As for display, [Jungle] took a trio of volt meters and wired them in to the PWM outputs on his PIC. With this, he was able to precisely control the position of the needle in the meter, and thus display the time.

In addition to displaying the time, [IronJungle] added a small temperature sensor to his build. By pressing a button below the seconds display, the clock is able to display the current temperature in Fahrenheit, Celsius, and Kelvin.

After the break you can check out a time-lapse video of [IronJungle]‘s voltmeter clock going through the hours.

[Read more...]

The $100 tri-copter

We’ve seen lots of budget tri-copters, but $100 seems like a heck of a deal to us! Watching this video, you can see this home made tri-copter is incredibly agile and seems to handle quite well. Whats amazing is that [hallstudio] claims that it cost roughly $100. That price is really good compared to even the cheapest multi copters out there.

Much of the manufacturing cost associated with this kind of thing has been removed as the body is just cheap wood from the local hardware store. He even did an admittedly sloppy rig for his tail rotor, not that it looks like it has hurt his performance.  One cool feature is the fact that you can fold the front arms backward, allowing for the tri-copter to be shoved into a bag for easy transportation.

You can find a complete parts list on his video, but it looks like maybe his cost doesn’t figure in the cost of the radio controller. There are no build instructions, but a quick google search leads us to the rcexplorer tricopter which seems to be the template he used. There are full build details there.

 

[via Hackedgadgets]

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