Multi-channel Analog Input Module Is A Good Jumping-off Point For Many Projects

June 19, 2012 by Mike Szczys 12 Comments

[Scott Harden] has already produced some projects which measure analog inputs. But he’s got plans for more and wanted a base system for graphing analog signals. You can see the small board next to his laptop which offers the ability to sample up to six signals and push them to a PC via USB.

The ATmega48 and a few supporting components are all you’ll find on that board. The USB connection is taken care of by an FTDI cable. He went that route because the cables are relatively cheap, easy to come by, and already have driver support on all the major operating systems. If you look at the screen you can see a window graphing one analog input in real-time. He wrote this in Python (which is once again a cross-platform tool) and it has no problem graphing all six inputs at once.

This is immediately useful as an upgrade to [Scott’s] ECG machine. His future plans include a Pulse Oximeter, EEG, and EEG.

You’ll Throw Your Back Out Playing This Analog TV Synth

May 15, 2012 by Mike Nathan 11 Comments

de-rastra

While CRT televisions fall to the wayside as more people adopt flat-panel TVs, the abundance of unused sets gives hacker/artist [Kyle Evans] an unlimited number of analog canvases on which to project his vision. He recently wrote in to share his latest creation which he dubs “de/Rastra”.

The “CRT Performance Interface” as he calls it, is an old analog television which he hacked to display signals created by moving the TV around. Fitted with an array of force sensors, accelerometers, and switches, the display is dynamically generated by the movements of whomever happens to be holding the set.

Signals are sent wirelessly from his sensor array to an Atmel 328 microcontroller with the help of a pair of XBee radios, where they are analyzed and used to generate a series of audio streams. The signals are fed into a 400W amplifier before being inserted into the CRT’s yoke, and subsequently displayed on the screen.

We’re sure [Kyle] is probably trying to express a complex metaphor about man’s futile attempts to impose his control over technology with his project, but we think it simply looks cool.

Check out [Kyle’s] work for yourself in the video below and give us your take in the comments.

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A New And Improved Magnetic Cello

April 17, 2012 by Brian Benchoff 9 Comments

Over the past few months, [Magnetovore] has been working on his magnetic cell project. It’s a very interesting instrument that seems right out of the electronic music explosion of the 1970s. Now, he’s ready to share his invention with the world, and we wouldn’t be surprised if we see this instrument being picked up by a few avant-garde musicians in the next few years.

Last September, we were introduced to [Magnetovore]’s magnetic cello. The original version used four ribbon sensors for each of the strings and had completely analog electronics, leaving us wondering why this cello wasn’t invented in the 70s. The new version of the cello keeps the analog electronics that sound remarkably like a real acoustic cello, but does away with three of the ribbon sensors. Now the cello has a single ribbon sensor being used as all four strings – to change which string is played, the musician just has to press a button on the ‘bow’.

There is a drawback to using only one ribbon sensor; it’s now impossible to play two strings simultaneously as on an acoustic cello. The electronics in [Magnetovore]’s original magnetic cello were monophonic anyway, so we’ll chalk this design change-up to reducing component cost.

After the break, you can check out a trio of very talented cellists playing [Magnetovore]’s magnetic cello. There’s the classic Pokemon Center theme, the Mario Bros. theme, as well a Bach minuet and a crazy improvisation showing off what the magnetic cello can do.

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Advent Calendar Of Circuits

December 16, 2011 by Mike Szczys 2 Comments

We missed 60% of it already, but luckily you can easily watch the back catalog of [Alan Yates’] 2011 Advent Calendar of Circuits. As with traditional Advent Calendars he’s got a treat for every day in December leading up to Christmas. Instead of chocolate, the treat is a video about a different electronic circuit.

We didn’t find a playlist link, but you can just head over to his YouTube channel as each day is clearly labelled in the video titles. He starts off with a current limiting voltage regulator. A couple of days later he busts out a metal detector that will be fun to play with. Day 7 brings an AM transmitter/receiver pair, and Day 12 illustrates a burnt-out Christmas light detecting tool which we’ve embedded after the break.

The sheer volume of projects he’s putting out every day is remarkable and delightful. He doesn’t even limit himself to one video a day, but has posted several ‘extra’ editions with quick, circuit demos. Continue reading “Advent Calendar Of Circuits” →

This Toy Intercom System Is Way Better Than A Pair Of Tin Cans And Some String

December 6, 2011 by Mike Nathan 36 Comments

toy-intercom-system

On his blog, [Kenneth Finnegan] recently showed off a replica of a fun toy he used to play with as a kid, a telephone intercom system. The setup is pretty simple, requiring little more than a pair of analog phones, a battery, and a resistor.

The phones are connected to one another using a standard telephone cable, but [Kenneth] uses a 9v battery to introduce a small bias current into the loop, allowing the speakers at either end to hear one another. He also added a small LED into the circuit so that there is a visual indication as to when both handsets are off hook.

The setup is very simple at the moment, though [Kenneth] does have some ideas in mind to enhance his intercom system. He hopes to tweak the remote phone to ring when the local phone is picked up, among other things.

Telephone technology is nothing new, but for just a few dollars (or less) your kids can be entertained for hours as [Kenneth] was way back when.

Continue reading to see a short video overview of the phone system, and be sure to share your ideas for enhancing it in the comments section.

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Multivibrator In Theory And Practice

December 1, 2011 by Mike Szczys 60 Comments

We must admit that we’ve been guilty of using a microcontroller to make two LEDs blink alternately in the past. It’s not the worst transgression, but it stems from our discomfort with analog circuits. Luckily, [Ray] published an illustrated guide on building multivibrator circuits. This is a simple method of assembling a two-output oscillator. All it takes is a pair of NPN transistors, which are then switched by on and off based on a resistor-capacitor (RC) timer.

[Ray] does a good job of walking us through how the circuit works at each stage of one complete cycle. You’ll need to read carefully, but the supplementary schematics he uses to water down snap shots of the various electrical states really helped us understand.

Of course, blinking LEDs isn’t the sole purpose of a multivibrator. It is a method of producing a clean square wave which can be used as a clock signal for TTL logic chips. Oh, who are we kidding, see the blinky goodness for yourself in the video after the break.

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Analog Test Interface For Your Computer

October 20, 2011 by Mike Szczys 6 Comments

Wanting to test the response curves on some analog parts, [Don Sauer] devised a way of using simple tools to graph analog tests on a computer. Here you can see the results of testing NPN, PNP, NMOS and PMOS transistors, but modifying the input circuitry would let you test just about anything you want.

[Don] is using an Arduino as the hardware interface. He needed some additional parts, like an op-amp and some passives. Instead of building this on a breadboard, he printed the circuit out on a piece of cardboard, hot glued the components in place, then wired them up. This will let him reuse the interface in the future, but is quicker than designing and etching a PCB.

He uses a Processing sketch to capture the test data streaming in from the Arduino. Once recorded, he uses SciLab to create the graphs. He also covers a method of sifting through the data using Octave, another open source program that feels somewhat like MATLAB.