Active analog filters can be found in almost every electronic circuit. Audio systems use filters for frequency-band limiting and equalization. Designers of communication systems use filters for tuning specific frequencies and eliminating others. To attenuate high-frequency signals, every data acquisition system has either an anti-aliasing (low-pass) filter before the analog-to-digital converter (ADC) or an anti-imaging (low-pass) filter after the digital-to-analog converter (DAC). This analog filtering can also remove higher-frequency noise superimposed on the signal before it reaches the ADC or after it leaves the DAC. If an input signal to an ADC is beyond half of the converter’s sampling frequency, the magnitude of that signal is converted reliably; but the frequency is modified as it aliases back into the digital output.
Designing active analog filters in minutes - [Link]
Bertho shared his NoLoop galvanic isolator:
I had a problem some time ago with a nasty ground-loop and that cost me the USB port on my old laptop. It took me a while to realize what had happened and it was a generic problem we all run into more often than we think. Time to solve this particular problem once and for all and make generic isolation for Serial and SPI ports.
NoLoop galvanic isolator - [Link]
Clemens Valens, Editor-in-Chief of Elektor Online and head of Elektor Labs, caught up with Peter Lomas, hardware designer for the Raspberry Pi single-board computer, earlier this year at the Embedded World 2013 trade show in Nuremberg, Germany. This is a longer version of an interview with Lomas published in Elektor’s May 2013 issue. The Lomas interview provided a one-year update on the rapid growth of interest in the Raspberry Pi since Elektor’s April 2012 interview with Eben Upton, one of the founders and trustees of the Raspberry Pi Foundation. The UK-based charitable foundation developed the inexpensive, credit card-sized computer to encourage the study of basic computer science in schools. In early 2012, the Raspberry Pi’s first production batches were arriving. Since then, more than 1 million boards have been sold.
Raspberry Pi: One Year Later, 1 Million Sold - [Link]
Boris Landoni present us an overview of todays microcomputer boards able to run Linux. He writes:
Today we present an overview of today’s market offering regarding ARM RISC microcomputer able to run a GNU/Linux distribution. And once again, this is just the beginning.While the growth of such a device segment was predictable, it wasn’t easy to predict such an explosion. In fact we now have an heterogeneous set of options, with different characteristics, requiring a different approaches to for the optimization of the GNU / Linux operating system. In this post we’ll try to present, on the one hand, the unifying elements of different devices and, secondly, to classify each device based on its best use cases.Let’s begin to point out a first list of devices to analyze, new ones appear every day but we’ll deal with them later.The ones we feature on this post are the following:
A Comprehensive Comparison of Linux Development Boards - [Link]
With DVR becoming increasingly common over the last few years, DirecTV has sought to distinguish its offerings on that front with multiple levels of service. At the top of the DirecTV DVR receiver options, the Genie offers a huge array of features on a powerful piece of hardware. You can get the newest Genie by signing up for DirecTV using www.SaveonTVDirect.com. For the average user, this means a better viewing experience; for the advanced user, this means the opportunity for interesting hacks; for the enterprising salvager, this means useful parts to collect from an unused or broken unit.
So let’s talk about all the uses you can get out of a Genie, whatever your experience level or goals. Read the rest of this entry »
How single board computers changing the maker community. Cabe Atwell writes:
Since the coming of the Raspberry Pi Model B, single-board computers (SBCs) have become a prevalent force in the development world. These pocket-sized devices have taken the online maker community in particular by storm, providing PC functionality to a plethora of open-source projects in amazingly compact, cost-effective, and low-power platforms.
It’s not an overstatement to say these tiny computers have engendered a technological revolution of their own by pushing the limits of technological creativity achievable in the palm of one’s hand. As an added benefit, SBCs have served as cheaply obtainable educational tools for teaching the ever-important concepts of computer science to the younger generation. Test engineers, those seeking to build one-off projects, and hobbyists have embraced, and appreciate, this mini computer platform. Similar to how the smartphone changed how we use phones, SBCs are poised to change how we approach embedded systems development.
The biggest-little revolution: 10 single-board computers for under $100 - [Link]
When the circuit is powered up, all of the transistors are off and stay off. C1 gets pulled up to Vp. When the switch is pushed, Q3 and Q2 turn on, since their base is pulled up. Q1 and Q4 are in turned on as well. Q1 keeps Q2 turned on and Q2 keeps Q3 turned on and Q3 keeps Q4 turned on. Q4 supplies current to the load. When Q2 is asserted it keeps pin 1 of SW1 at ground.
When the switch is pulled low again, the base of Q3 is tied to ground, because Q2 is on, and the chain is broken an all of the transistors turn off.
C1 and R1 and R5 form the time constant for the debounce circuit. Adjust these values for an appropriate debounce time.
Latching Momentary Switch for breadboard - [Link]
Mizchief100 @ instructables.com writes:
This project was my take on a DIY visual impairment aid that uses haptic and sound feedback. Basically it uses a distance sensor to measure how far objects are from it and then it beeps/vibrates accordingly (far away is slow vibrate/long beep delay and close up is fast vibrate/quick beeps). Real quick I’d like to acknowledge that I’m not the first to do something like this, but I have added many things to it that are different from designs I have seen. This isn’t being used for commercial purposes but just as a guide for others to make them for people who would actually benefit from having them.
VIA (Visual Impairment Aid) - [Link]
kmpres @ instructables.com writes:
My urge to build this project came when my wife’s car refused to turn over after a three day weekend away. Here in Tokyo, during winter, the temperature can drop to the low 20’s (F) at night and since we have no garage, her car just has to endure the cold as best it can. Many people don’t realize that you don’t have put up with repeated jump-starts or run to the nearest garage and plunk down 7,500 yen ($85) for a new battery every time this happens. Your old battery may just have built up a layer of lead sulphate crystals on its plates and that is preventing the acid from contacting them over their full surface area. This is caused by subjecting the battery to long periods of insufficient charge, as in the cases of unplugged golf carts over the winter, infrequently used automobiles, and PV systems that don’t get enough sunlight to charge their batteries. The result is a great reduction in the battery’s ability to produce electricity.
Desulfator for 12V Car Batteries, in an Altoids Tin - [Link]