TL084 die blocks

Ken Shirriff Found Butterflies In His Op-Amp

In 1976, Texas Instruments came out with the TL084, a four JFET op-amp IC each with similar circuitry to Fairchild’s very popular single op-amp 741. But even though the 741 has been covered in detailed, when [Ken Shirriff] focused his microscope on a TL084, he found some very interesting things.

JFETs on the TL084 op-amp

To avoid using acid to get at the die, he instead found a ceramic packaged TL084 and pried off the cover. The first things he saw were four stabilizing capacitors, by far the largest structures on the die and visible to the naked eye.

When he peered into his microscope he next saw butterfly shapes which turned out to be pairs of input JFETs. The wide strips are the gates and the narrower strip surrounded by each gate is the source. The drain is the narrow strip surrounding each gate. Why arrange four JFETs like this? It’s possible to have temperature gradients in the IC, one side being hotter than the other. These gradients can affect the JFET’s characteristics, unbalancing the inputs. Look closely at the way the JFETs are connected and you’ll see that the top-left one is connected to the bottom-right one, and similarly for the other two. This diagonal cross-connecting cancels out any negative effects.

[Ken’s] analysis in his article doesn’t stop there though. Not only does he talk more about these JFETs but he goes over the rest of the die too. It’s well worth the read, as is his write-up about the 741 which we’ve also covered.

Never Go To The Office Breakroom Again

If you’re tired of having to make small talk with random people in the office break room every time you need a cup of coffee, or simply don’t have the time to get up to pour yourself some more, it would be nice if there was a way you could have your cup filled for you, right at your desk. With this new drink dispenser, you won’t have to get up or even pour your drinks yourself!

We’ve certainly seen plenty of automatic drink makers, but those are more suited to parties and complicated drink mixing. This beverage dispenser is more for the person who knows their tastes and simply wants to save some time. It’s also much simpler, using a peristaltic pump for serving a single liquid from a large bottle into a glass, and using a load cell to know when to stop filling. The peristaltic pump is a little slow though, so it’s best to set the glass back in the dispenser and let it top you off each time.

We’re a big fan of time savers around here, especially when it comes to improving workflow. Of course, the best time saver is a clean, well-organized shop which will help you out whether you’re building a drink dispenser or anything else.

Continue reading “Never Go To The Office Breakroom Again”

Wired And IBM Explain Quantum Computing To Students From Grade School To Grad School

Have you ever heard the old axiom that if you want to design a simple system, ask yourself if your grandmother could use it? Maybe that was on Wired’s mind because they asked a quantum computing expert — particularly IBM’s [Dr. Talia Gershon] — to explain what exactly quantum computing is at 5 levels. In the video they shot, which you can see below, [Dr. Gershon] talks to a younger child, a teenager, an undergraduate computer science student, a graduate student, and then a physicist.

We enjoyed some of the analogies of spinning pennies and the way she was able to bring the topic to an appropriate level for each of the participants. Truthfully, the final segment with the physicist ([Dr. Steven Girvin] was more of a conversation than an explanation, but it was interesting to hear his views on fault tolerance and how likely certain things were to occur in the near future.

Continue reading “Wired And IBM Explain Quantum Computing To Students From Grade School To Grad School”

Hackers Want Cambridge Dictionary To Change Their Definition

Maybe it’s the silly season of high summer, or maybe a PR bunny at a cybersecurity company has simply hit the jackpot with a story syndicated by the Press Association, but the non-tech media has been earnestly talking about a call upon the Cambridge Dictionary to remove the word “illegal” from their definition of “Hacker”. The weighty tome from the famous British university lists the word as either “a person who is skilled in the use of computer systems, often one who illegally obtains access to private computer systems:” in its learners dictionary, or as “someone who illegally uses a computer to access information stored on another computer system or to spread a computer virus” in its academic dictionary. The cybersecurity company in question argues that hackers in fact do a lot of the work that improves cybersecurity and are thus all-round Good Eggs, and not those nasty computer crooks we hear so much about in the papers.

We’re right behind them on the point about illegality, because while there are those who adopt the hacker sobriquet that wear hats of all colours including black, for us being a hacker is about having the curiosity to tinker with anything presented to us, whatever it is. It’s a word that originated among railway modelers (Internet Archived version), hardly a community that’s known for its criminal tendencies!

Popular Usage Informs Definition

It is however futile to attempt to influence a dictionary in this way. There are two types of lexicography: Prescriptive and Descriptive. With prescriptive lexicography, the dictionary instructs what something must mean or how it should be spelled, while descriptive lexicography tells you how something is used in the real world based on extensive usage research. Thus venerable lexicographers such as Samuel Johnson or Noah Webster told you a particular way to use your English, while their modern equivalents lead you towards current usage with plenty of examples.

It’s something that can cause significant discontent among some dictionary users as we can see from our consternation over the word “hacker”. The administration team at all dictionaries will be familiar with the constant stream of letters of complaint from people outraged that their pet piece of language is not reflected in the volume they regard as an authority. But while modern lexicographers admit that they sometimes walk in an uneasy balance between the two approaches, they are at heart scientists with a rigorous approach to evidence-based research, and are very proud of their efforts.

Big Data Makes for Big Dictionaries

Lexicographic research comes from huge corpora, databases of tens or hundreds of millions of words of written English, from which they can extract the subtlest of language trends to see where a word is going. These can be interesting and engrossing tools for anyone, not just linguists, so we’d urge you to have a go for yourself.

Sadly for us the corpus evidence shows the definition for “Hacker” has very firmly trended toward the tabloid newspaper meaning that associates cybercriminality. All we can do is subvert that trend by doing our best to own the word as we would prefer it to be used, re-appropriating it. At least the other weighty tome from a well-known British university has a secondary sense that we do agree with: An enthusiastic and skilful computer programmer or user“.

Disclosure: Jenny List used to work in the dictionary business.

James Bruton's mini electric bike

Building A Mini Electric Bike In Between Projects

What do you do when you suddenly find you have some free time because you’re waiting on parts or have run up against other delays for your current project? If you’re [James Bruton], you design and build a mini electric bike.

Being a prolific builder, [James] already had the parts he needed. Some of them were left over from previous projects: a small motor, a 24 volt LiPo battery, an SK8 electronic speed controller, and a twist grip for the handlebars. He cut a wooden frame using his CNC machine and 3D printed various other components. Normally he uses ABS for motor mounts but this time he went with PLA and sure enough, the motor heated up and the mounting screws got hot enough to melt the plastic. But other than that, the bike worked great and looks like a polished, manufactured product. How many of us can say the same for our own unplanned projects using only parts from around the workshop? Check out his build and watch him whizzing around on it in the video below.

As for the former projects from which he had leftover parts, he says that some came from skateboard projects such as his pimped out electric LEGO longboard.

Continue reading “Building A Mini Electric Bike In Between Projects”

Controlling Robotics Visually

The world — and the Hackaday Prize — is filled with educational robots. These are small, wheeled robots loaded up with sensors, actuators, a few motor drivers, and some sort of system that is easy to program. The idea behind these educational robots is to give students an easy-to-use platform to test out code, learn inverse kinematics, and realize odometry is a lot harder than you think it is. Give these kids some time and patience, and you’ll have a fleet of Battlebots at the end of the semester, if the teacher is cool.

But there’s a problem with all educational robots. The programming. For someone just starting out in robotics club, being able to code isn’t a guarantee. You need an easy to use programming interface. This project for the Hackaday Prize gives all students a great visual programming interface. It’s basically like the first generation of Lego Mindstorms, only you don’t need a weird IR tower attached to a serial port.

Of course you can’t program a robot without a board, and this project brings it in spades. The brain for this platform is built on an ARM microcontroller, has Bluetooth, supports up to six DC motors, twelve analog inputs, PWM and serial ports, and all the ports are color-coded for kids who can’t read so good.

This is a visual programming environment, though, and with that, you get a fancy IDE filled with loops that wrap around commands, IO access that’s in easy to read blocks, and control software that gives students a dashboard filled with buttons and odometers and the video feed from the camera. It’s a great Hackaday Prize entry, and an excellent way to introduce kids to robotics.

LEGO: The Kristiansen Legocy

Whether you are young, old, or a time traveling Vulcan, something unites all of us globally: the innocent LEGO blocks that encourage creativity over spoon-fed entertainment. Have you noticed the excess of zombified children and adults alike drooling over their collective screens lately? Back in the ancient times, all a child needed to create hours of joy were plastic interlocking bricks and a place for their parents to trip over them. The LEGO Group harbored the inspiration of our childhood inventiveness, and none of it would have been possible without the founder, Ole Kirk Kristiansen (or Christiansen). The humble carpenter from Denmark forever made his mark on the little Scandinavian country, one brick at a time.

Well, maybe not at first. You see the plastic LEGO bricks we all know and love were initially made of wood. And they were also not actually bricks.

Continue reading “LEGO: The Kristiansen Legocy”