I have in my notebooks from  a complete description of the tunnel diode,” the speaker told the audience at a symposium on innovation at the MIT Club of New York, in New York City, in December 1976. It was quite a revelation, because the speaker wasn’t Leo Esaki, who had won the 1973 Nobel Prize in physics for inventing the tunnel diode in the late 1950s. It was Robert N. Noyce, cofounder of Intel Corp., Santa Clara, Calif.; inventor of the first practical integrated circuit; and a man who, as far as anyone knew before that speech, had no connection to the most storied electronic device never to be manufactured in large numbers.
Engineers coveted the tunnel diode for its extremely fast switching times–tens of picoseconds–at a time when transistors loped along at milliseconds. But it never found commercial success, though it was occasionally used as a very fast switch. As a two-terminal device, the diode could not readily be designed for amplification, unlike a three-terminal transistor, whose circuit applications were then growing astronomically. Nevertheless, the tunnel diode was a seminal invention. It provided the first physical evidence that the phenomenon of tunneling, a key postulate of quantum mechanics, was more than an intriguing theory.
Quantum mechanics, the foundation of modern physics, is an elaborate conceptual framework that predicts the behavior of matter and radiation at the atomic level. One of its most fundamental notions is that the exchange of energy at the subatomic level is constrained to certain levels, or quantities–in a word, quantized.
Many of the core concepts and phenomena of quantum mechanics are almost completely counterintuitive. For example, consider a piece of semiconductor joined to an insulator. From the point of view of classical physics theory, the electrons in the semiconductor are like rubber balls, and the insulator is like a low garden wall. An electron would have no chance of getting over the barrier unless its energy were higher than the barrier’s. But according to quantum mechanics, the phenomenon of tunneling ensures that for certain conditions an electron with less energy than the barrier’s will not bounce off the wall but will instead tunnel right through it.
This time we’re going to be doing an autopsy on a Heathkit Grid Dip Meter. Lets begin!
The Heathkit Grid Dip Meter was initially released in 1953 for $20. The designed use of the grid dip meter is to measure high-frequency radio and television equipment. As you’ll see from the schematic on the last page, it is basically just a high-frequency oscillator. There were several listed uses for this device, including detecting resonant frequencies and acting as a tone generator.
A great, non-expert explanation of the Fourier Transform by Stuart Riffle over at AltDevBlog.
A very long time ago, I was curious how to detect the strength of the bass and treble in music, in order to synchronize some graphical effects. I had no idea how to do such a thing, so I tried to figure it out, but I didn’t get very far. Eventually I learned that I needed something called a Fourier transform, so I took a trip to the library and looked it up (which is what we had to do back in those days).
Eventually, I was able to visualize how it works, which was a bit of a lightbulb for me. That’s what I want to write about today: an intuitive way to picture the Fourier transform. This may be obvious to you, but it wasn’t to me, so if you work with audio or rendering, I hope there’s something here you find useful.
Disclaimer: my math skills are pitch-patch at best, and this is just intended to be an informal article, so please don’t expect a rigorous treatment. However, I will do my best not to flat-out lie about anything, and I’m sure people will set me straight if I get something wrong.
Please visit the campaign page to see more photos of the stickers and to see how they can be used.
Here, I will write a bit about the background story, tech details, and manufacturing processes that went into making them.
Circuit stickers are peel-and-stick electronics for crafting circuits. In a nutshell, they are circuits on a flexible polyimide substrate with anisotropic tape (or “Z-tape” — so named because electricity only flows vertically through the tape, and not laterally) laminated on the back.
The use of Z-tape allows one to assemble circuits without the need for high-temperature processing (e.g. soldering or reflow), thereby enabling compatibility with heat-sensitive and/or pliable material substrates, such as paper, fabric, plastic, and so forth.
This enables electronics to be integrated in a range of non-traditional material systems with great aesthetic effect, as exemplified by the addition of circuit stickers to fabric and paper.
I purchased a cheap USB power pack, thinking it would be ideal for powering small projects. But it automatically shuts off if the device isn’t drawing a lot of power, since it’s meant for charging cell phones. Here’s a 2 transistor circuit I built this morning that keeps it on with very little battery drain by using brief pulses.
Today’s teardown subject has been waiting for its turn for a while- I picked it up at the last Design East conference in Boston in 2012. There, Microchip and Energizer were talking about low power design and using these Schick Hydro 5 power razors as an example. Hot on the heels of my repair of a Philips Sonicare toothbrush, this seems to be a good fit for a comparison. Both things do essentially the same thing- they shake, light up some LEDs and not much else.
A peltier module is a solid state device often used for doing cooling. Their found in some portable coolers for carrying food to the beach or in water dispensers like the one shown below.
While they’re useful for those purposes, they’re not very efficient. Only around 5% of the electrical energy used to power them gets used for cooling. I decided to do the simple efficiency test shown here. I wasn’t testing the module directly, but instead testing how efficiently it could cool 250ml of water.
While Eagle3D is designed for rendering 3D views of a board rather than creating a solid model, this is nonetheless a useful tool to explore. Be prepared to step over a few hurdles to run some of the software that might not run natively on recent OSes. Think this elaborate dance is worth it worth it? Check out this visualization linked here.
Using Eagle3D and POV-Ray, you can make realistic 3D renderings of your PCBs. Eagle3D is a script for EAGLE Layout Editor. This will generate a ray tracing file, which will be sent to POV-Ray, which in turn will eventually pop out the finalized image of your PCB.
Over the last few weeks we’ve been building 3D models of our projects in Google SketchUp using the EagleUp script. This script makes a 3D model of the board from Cadsoft Eagle board (.brd) files, and populates it with preexisting models of components.
Once you have a 3D model in SketchUp you are free to evaluate it, build custom enclosures around it, or interface your model with others. This tutorial will help you build 3D models of your projects.
NOTE: Be advised that to build full 3D models of your projects you will have to have models for all your components. Some are available with the EagleUp script, some via the 3D warehouse, and some from our own library.
Usually you use eagle to design your printed circuit boards (PCBs) only in 2 dimensions (when not considering the layers as 3rd layer). This gives you some headaches for narrow space designs like in small cases.
The common solution until now is to export your board with eagleUp and assemble it with a case in Sketchup. This also gives you some drawbacks. The most important to me was that the Sketchup files are mesh based like the data used for 3D printing usually, but for further use in CAD systems this is not really usable. You also will not be able to get a STEP model that you can give to your costumers out of this data.
Another solution is to use eagle3D, which gives you photorealistic renders of your boards. This images (or even videos) are really good for marketing brochures, but this way makes it impossible for you to play with your 3D models to estimate how much space is left in your case.
The solution I found was to write a macro for FreeCAD that interprets the XML Data that Eagle 6 uses to save your board (the .brd file). This means that my script reads the outline of the pcb and extrudes it with the thickness you specified in eagle. The XML file also contains the names of your parts, which you can map to 3D CAD Models (STEP Models) of them. The last step is to assemble the parts and the board. For more information on how to use it see my github repository.
The only drawback of the freecad solution is that somehow the colors of STEP models get lost – at this time I expect it to be a freecad problem that might be fixed in the future.
As a graphic designer turned engineer, Ben has a treasure trove of tips and tricks for making your electronics projects look awesome. In this episode he’ll provide insight on the process of designing, explain some parameters to keep in mind, as well as share his thoughts in creating an aesthetically pleasing design.
This two-part design unites a tight-fit interior cavity for the electronics and components and a smooth, organic external shell with a handgrip — and it can be printed out on most desktop printers these days:
It’s one of the best RFID/NFC breakout boards around, and since I’ll be using mine in a Horse Barn environment, I needed an enclosure that could stand up to wear and tear, as well as be functional and easy to use. This is my 2nd attempt to make such an enclosure using Blender and my trust MakerBot Replicator – I have ideas for a 3rd design in the works now.
The board is made by Kevin Townsand of Adafruit, and is a particularly well-made product – really ahead of it’s time.
PN532 NFC/RFID controller breakout board – v1.3: The PN532 is the most popular NFC chip, and is what is embedded in pretty much every phone or device that does NFC. It can pretty much do it all, such as read and write to tags and cards, communicate with phones (say for payment processing), and ‘act’ like a NFC tag. If you want to do any sort of embedded NFC work, this is the chip you’ll want to use! (read more)