Superpositioned

I’m a sucker for interesting robots. Especially if they are built out of Legos. Everybody loves the Legway, but you have to admit that the concept is overly simplistic. The real challenge is building the system around the limited resources of Lego’s RCX.

Now meet another balancing robot courtesy of Maurits Kooiman on Lugnet. This one balances on one wheel and apparently uses two RCX bricks and four sensors along with three tires to maintain balance on the axis perpendicular to its unicycle. The robot balances on the main axis by directly powering the wheel. The axis perpendicular to its unicycle is balanced by the set of rotating tires. The fourth tire seems to be a freely swingy pendulum, but it may in fact be controlled by yet another motor. Check out the video!

I officially declare this site back in action! I been ignoring it for too long. Over the past week, I have updated Typo and designed a new layout. This is not the completely final version, though. The header/logo and advertisements need some work. The previous layout performed very well in that department. Hopefully this layout will make up for the difference by attracting more repeat visitors.

As you can see, the new layout is significantly better on the eyes. Unfortunately, it has some issues with Internet Explorer 6. Hopefully I can figure out what is causing the extra space to appear. Here is a quick list of the updates:

1. Windows Vista Typefaces: Vista includes some “cute” fonts. If you have them installed, then the new layout uses Calibri. The best way to describe it is “semi-serif.” It actually replaces Times New Roman as the default font in Office 2007.

2. Fluid width and resolution independence. Go ahead, resize your text. The sidebar automatically resizes as well! Of course I also added fluid width. (Fixed width is useless.)

3. The colors are kinder on the eyes. I grew tired of deep red and flashy magenta.

4. Better readability around the ads. I might regret this one, but at least you can read through the copy without getting a headache now.

Watch for a new post detailing my upcoming endevors!

The Digg.com headlines for today include research about bacterium that produces electricity by consuming sugar. The Escherichia coli bacteria actually excrete hydrogen after consuming sugar. An electric fuel cell is then powered by the hydrogen.

The team fed Escherichia coli bacteria diluted caramel and nougat waste. The bacteria consumed the sugar and produced hydrogen, which they make with the enzyme hydrogenase, and organic acids. The researchers then used this hydrogen to power a fuel cell, which generated enough electricity to drive a small fan.

They are also using the bacteria to recover palladium metal from the spent catalytic converters of older vehicles.

Clive Maxfield recently posed the Black Box Brain Boggler in the Logically Speaking column of May’s EE Times. The original article was incorrect and posed an overly simple problem. In fact, the real problem is much more difficult, but possible none the less.

At first, this appears to be deceptively simple. We start with a black box with three inputs–A, B and C–and three outputs (see below). The outputs, which we may name !A, !B and !C, are the logical inversions of the inputs.

The challenge is implementing this black box with only two inverters, a bucket of basic gates, and without a hard coded binary 0 or 1. The bucket of gates presents two levels of difficulty. The former being far easier than the latter. In fact, the first bucket should be easy for any digital design student to solve.

1. The bucket of basic gates contains AND, OR, and XOR gates. Remember, you cannot connect any of the inputs directly to a binary 0 or 1.

2. The bucket contains only AND and OR gates. The solutions are extremely complex, but do exist!

He recently posted the clarifications and some purposed solutions on DesignLine. If you are curious, here are the spoilers for challenge one and two. If you enjoy proofs, there are some more logic puzzlers for your unsatisfied brain.

My last project brought up the subject of capacitive touch sensing. You may not have realized this, but capacitive touch sensing is currently on the forefront of electronics. Mechanical touch sensors are known to wear and ‘push-less’ sensors are just cooler. In case you did not know, the scroll wheel on an Ipod uses an array of capacitive sensors along with the infamous touch lamp.

For the engineer in you, Planet Analog has a lengthy overview. Basically, you design a circuit that is highly dependent on the value of a small capacitor. The capacitance in a finger then causes a significant and detectable change in the circuits output.

The doorknob touch alarm functions in just this manner. It does its job, but is not as precise as more complex circuits. For more schematics, check out Discover Circuits. A recent article on DesignLine proposed that this interface be adapted to mobile phone keypads.

I recently found a doorknob touch alarm schematic while browsing Discover Circuits’ archives. The project was originally intended as a present for my brother’s dorm room, but a bad capacitor and the lack of a proper oscilloscope caused delays. It has not made it off the breadboard, and it probably will not until his next semester. The circuit contains a few basic elements, an flip-flop based oscillator, a set of delays, a flip-flop as a sensor, and the audible alarm.

The Four Dees of Analog is a story written by ADI Fellow Barrie Gilbert about a job interview circa 2025. It is crazy to imagine being interviewed over live HDTV quality teleconference with noncontact stress monitors live at the site. The story goes on to describe the differences between simply collecting information and aquiring knowledge by relating and applying that information.

Of course, this is an article in Analog Devices’ Analog Dialogue so the Sci-Fi aura quickly fades into an advertisement for analog design. In the surrounding of a digital world, the story is a great reminder that analog instrumentation is still all around us. Additionally, it highlights the benefits and challenges of analog circuitry.

Stolen from Now to offend some maths students on Mark’s Things*:

What is the difference between a Ph.D. in mathematics and a large pizza?

There are two major microcontrollers in the hobby domain, the popular PIC and Atmel’s AVR line. PICs are tried and true in both commercial and hobby implementations, but the Atmel AVR offers affordable programming solutions, a free development environment, a free assembler and a stable gcc toolkit that work across the entire AVR line.

Depending on the application, charging batteries can be complex process. Charging methods range from constant voltage to pulsed and random charging. Once power is being delivered back into the battery, you have to know when to stop charging!

Once a battery is fully charged, the charging current has to be dissipated somehow. The result is the generation of heat and gasses both of which are bad for batteries. The essence of good charging is to be able to detect when the reconstitution of the active chemicals is complete and to stop the charging process before any damage is done.

Typically, common household batteries are charged with a current that is kept constant and relieved when the batteries reach a predetermined potential. However, solar cells typically generate a constant voltage of 0.5V and a varying current that depends on the amount of collected light. As such, a consant voltage charging model is easier to implement. I found two respectable tutorials on building your own charger:

1. AA Battery Solar Charger
2. Clean Power’s Solar battery project charger

The first solution uses a diode to stop the batteries from discharging when there is no sunlight. I highly reccomend including this protection. Unfortunately, neither project implements a charge limit. You have to remove the batteries and test their charge with a multimeter. A shunt regulator is the simplest way to regulate the upper limit.