You’ll wanna pull up a really comfy chair before you dive into this one, but have you ever found yourself digging through Eagle’s 317,424 different canned footprints, hoping one is kinda, sorta, almost, maybe good enough for that new sensor you found on Digikey? Shamelessly dig and despair no more! … Our new mammoth guide on creating manufacturable footprints in Eagle is here to ween you off that nasty canned footprint habit, and get you firmly on the road to non-dependency!
This page describes how you can use an Atmel ATmega32U4 (e.g. an Arduino Leonardo, Teensy or clone) and a DCF77 receiver to build a (hot-pluggable) HID USB real-time (radio) clock (I’ve named it dcf77-hid-usb-rtc), for usage with Linux systems.
Because it is a radio clock, it will always have the exact time, at least as long as it will receive a signal from the German DCF77 time code transmitter in Mainflingen. So it is perfectly usable as a reliable stratum 0 time source for your network (if a resolution of one second fits your needs). As this isn’t a scientific paper about accurate and reliable real-time clocks, I will not go further into the details of time keeping. As a first step you might read the Wikipedia article about NTP.
The overall cost for one of those thingies I’m describing here is about 25€, which isn’t really cheap. But I find it a valuable thingy because the result is a hot pluggable RTC, usable by almost any device which has USB. So it’s very likely you will use it for much longer than the computer you currently want to build or search it for….
Now here are some wedding vows that the Adafruit crowd can get behind — soldering a project together that lights up to say “I DO” as a metaphor for the marriage contract. Fascinating! From Bill Porter’s blog:
When it came time for Mara and I to draft our wedding ceremony we pondered how we could incorporate an element from our theme. We had 4 days to go and only some vague ideas. Mara bought some wood letters to spell out ‘I Do’ and wanted to use them in the ceremony. We also joked about using a soldering iron during the ceremony; but how could we do it tastefully? Then it hit us, a common wedding ceremony know as the “Fishermen’s Knot” could be reworded for something a little more geeky. Yes, we really did solder some wires together in the middle of our wedding, with a Weller soldering iron Mara bought me for a past birthday no less. And you won’t believe what PCBs came in handy for the build…
Ok, this post will be short because this project was thrown together 4 days before the wedding and we didn’t have time to stop and document the steps. We were set to get married and still had a lot to do, as evident by the mini-maker space we created in my parents house (see below).
Mara bought the letters at a local hobby store. I sketched out a rough outline of evenly spaced LEDs and went to work creating the holes with a drill press. A coat of blank paint and then my best man Dan went to work soldering wires to all those LEDs. Next we had to figured out a way to control those LEDs. In a pleasant case of coincidence, the boards I hijacked to ask my bride to marry me 2 years ago were designed to control large numbers of LEDs. Yes, the boards that asked “Mara Will You Marry Me?” were used to run letters that said ‘I Do’ during our wedding ceremony.
Last week, Vishay announced that it’s acquiring MCB Industrie S.A, a manufacturer of specialty resistors. Acquisitions have been a key piece of Vishay’s strategy, so we took a look at its track record to see the effect on market pricing of the target company’s products. (We used Octopart’shistorical pricing data.)
Today would be the 115th birthday of Harold Stephen Black, who invented the negative-feedback amplifier in 1927. The story goes that Mr. Black was taking the ferry from New Jersey to New York City (where Bell Labs was then located), and while on the boat he was struck by the idea to use negative feedback to linearize an amplifier stage.
The idea of negative feedback is a powerful one, because it provides a means to construct amplifiers with precise gain characteristics from parts with less than ideal specs. This makes it easier to build circuits with interchangeable, off-the-shelf parts. Gain can be adjusted using passive components, which are cheaper and easier to adjust.
Distortion and intermodulation are reduced significantly, and bandwidth is greatly increased. It also enables the construction of higher order filters without the use of inductors, which are heavy and prone to other problems. Though initially developed for vacuum tubes, the idea is very useful in transistor circuits, which can have wildly varying beta characteristics, even among devices on the same chip.
There are a lot of things to like about the video above, but my favorite part is the way he talks so earnestly about his failures, before finally succeeding.
In the June 2012 issue of Nuts & Volts, they did a spread about making a soil moisture sensor with an iPhone interface:
And when I heard my girlfriend say that she has trouble remembering to water her plants, I put two and two together.
Most of the N&V article discussed the code required to interface with the iPhone, but the important part for me was that their soil moisture sensor was nothing more than a simple conductivity sensor. The more water in the soil, the lower its resistance.
Such a sensor doesn’t measure soil moisture in any kind of universal unit, but for a single sensor in a particular soil sample, the measured conductivity is repeatable and proportional to the moisture level. I call these conductivity units “AMU”s or “Arbitrary Moisture Units”.
Each month this year, we’re exploring a different electronic component, delving into what it is, how it works, and how you use it in projects. Last monthwe looked at batteries. This month, we’ll tackle the resistor, the job of which is to limit the flow of electricity and thereby control it, guiding it toward one component while protecting another. As always, we’ll start things off with an introduction to resistors via an edited excerpt from Charles Platt’s essential Encyclopedia of Electronic Components: Volume 1.
Nothing is as fast and fun as prototyping on a breadboard, but at some point you will find that the chips you want to work with are only available in non-breadboard-friendly SMT/SMD (Surface Mount Technology/Surface Mount Device). Unlike most DIP chips and resistors, SMT parts do not have the leads going through holes in the PCB. Instead, they ‘float’ on top, with often-rectangular solder pads.
Although you may one day decide to use CAD software for laying out a custom PCB for these parts, you can do yourself a favor and prototype with SMT breakout/adapter PCBs. In this mini tutorial we’ll go over how to use these. It’s not hard, once you have the experience!
My first computer was a Texas Instruments TI-99/4A. Longtime readers may remember a previous article where we implemented TI-99/4A BASIC as a Scripting Language for modern computers. Recently I got nostalgic for the actual hardware so I got my 99 out of the closet where it had been for a decade or more.
There have been many studies of the causes of tombstoning; some published, some not. They tend to focus on a single process parameter as the root cause of tombstoning. However, there is no single process change that is a sure cure for tombstoning! Those that claim otherwise are either uninformed or trying to sell you something. Rather than limiting your view to a single solution, EFD recommends you heed all of the studies. Like pieces of a puzzle, each study does not reveal the whole picture, but looked at all together, the picture is clear.
The issue of tombstoning has risen to prominence because, while components and assemblies have become much smaller over the last decade, overall assembly processes have remained much the same. As components become smaller, so should your process windows.