Why Wasn’t This Magnetic Cello Made In The 70’s?

September 22, 2011 by Brian Benchoff 34 Comments

[magnetovore] made himself an electronic cello. Instead of pulling a few cello samples off of an SD card, he did it the old school analog way. The finished build is really impressive and leaves us wondering why we haven’t seen anything like this before.

[magnetovore] uses a permanent magnet to play each ‘string’. A lot of details are in this post and [magnetovore]’s provisional patent (PDF warning). From what we can gather, each string is a resistive ribbon sensor connected to a voltage controlled oscillator. The output of the VCO is sent to a variable gain amplifier that is controlled by a coil of wire and the magnetic ‘bow’.

From the video (after the break), [magnetovore] already has an amazing reproduction of the cello sound. It’s a bit electronic on the lowest parts of the C string, but with a little bit of processing it could definitely pass for an acoustic instrument. We’re left wondering why we haven’t seen anything like this cello before. VCOs and VGAs were the bread and butter of the old Moogs and even the ancient ondes martenot. Ribbon controllers were being attached to electronic instruments back in the 50’s, so we’re really at a loss on why a magnetic cello is new to us. If any Hack A Day readers have seen anything like this before, leave a message in the comments.

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Record Sound Without A Microcontroller

September 15, 2011 by Brian Benchoff 14 Comments

For his A-level electronic course work, [Andrew] decided to build a digital sound recorder that doesn’t use a microcontroller.

[Andrew]’s build captures audio from an on board microphone at 8000 samples/second. The audio is digitized into 8-bit sound data and sent to an SRAM. The recording and playback functions are controlled entirely by 4000-series logic chips. He admits the sound quality is pretty poor; this is mostly due to the 8kHz sample rate. In some circles, though, a terrible sample rate is seen as being pretty cool so we’re not going to say [Andrew]’s build is useless.

There’s some pretty smart design choices in [Andrew]’s build, like a cut off filter on the microphone set at 4000 Hz (the Nyquist frequency of his system). For the recording medium, he used an SRAM that can hold about half a megabyte of data. At 8000 samples/second, [Andrew]’s build can store a little more than 60 seconds of audio. The build may not be a logic chip computer, but there’s not any question in our mind that [Andrew] learned something. Check out [Andrew]’s 66-page coursework report here (PDF warning).

The Passing Of Bob Pease

June 21, 2011 by Mike Szczys 36 Comments

We are saddened by the recent passing of [Bob Pease]. You may not be familiar with the man, but his work has touched your lives in more ways than you can count. As an electronics engineer who specialized in analog components he was responsible for hardware that made some of the electronics in your life possible, and designed components that you’ve probably used if you dabble in electronic design.

EDN has a lengthy obituary celebrating his life and accomplishments. [Bob] was part of the 1961 graduating class at MIT. He started his career designing tube amplifiers before finding his way to a position at National Semiconductor about fifteen years later. Throughout his career he worked to promote education about analog electronics both through written text, and more recently as the host of Analog by Design, an online video program where a panel of experts discuss the ins and outs of electronics.

[Bob] was killed in an automobile accident on June 18th at the age of 70.

[via Make]

[Jeri’s] Dress Lights Up When Someone Invades Her Personal Space — Step Back Nerds!

June 1, 2011 by Mike Szczys 34 Comments

[Jeri] threw down the geeky fashion gauntlet by building this LED enhanced dress. She chose to assemble the project for her trip to BarBot 2011, and we can’t think of a more appropriate setting for such a garment. It uses a motion sensor to set off a delayed pattern of blue lights hidden underneath the fabric.The best part of the hack is the instamatic camera. It looks like a fashion accessory, but it’s really hiding all of the circuitry for the lights.

Inside the camera a PIR sensor waits until it detects motion, sending a signal through an op-amp to the trigger circuitry. A 74LS14 Schmitt Trigger chip teams up with some resistor-capacitor timer circuits to build a delay chain for the LEDs. This way, after motion is detected the LEDs come on and off in a staggered pattern that doesn’t require a microcontroller and is very pleasing to the eye. See the Analog win for yourself after the break.

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Analog Projection Clock So Simple You Should Have Thought Of It

May 4, 2011 by Mike Szczys 29 Comments

The image you see above is the result of a simple analog projection clock. It shows the time on the ceiling. We have one in our bedroom but it’s a red digital display which we don’t think is nearly as fun as this clever hack. Grab a cheap analog clock, a mirror, and a white LED and you can build your own.

The mirror is going to reflect light from the LED onto a ceiling or other surface. It acts as the clock face. The tick marks for each hour were made by scratching the reflective material (often called the silvering) from the back of the mirror. A hole is drilled at the center of the class and the analog clock is mounted with its hands on the business side. The one problem with this setup is that since the light is being reflected, the clock will appear to run backwards. Not a problem, if you just reverse the polarity of the coil which moves the clockwork the projection will move in the expected clockwise direction.

[via Make]

Hacking Analog Phones For VOIP

April 23, 2011 by Mike Nathan 30 Comments

analog_phone

[Tyler] has been using Google Voice extensively for some time now, but he hasn’t quite found a microphone/speaker setup he is happy with. He tried a headset, but that just didn’t do it for him.

While browsing around at his local thrift store, he came across an old Model 500 rotary phone for just a few dollars and decided it just might do the trick. Once disassembled, he mapped out the circuitry and got busy wiring up the handset to a pair of 3.5 mm stereo plugs – one each for the earpiece and microphone.

Once everything was reassembled, he hooked it up to his computer and gave it a spin – success!

While he is happy with how the phone works at the moment, he already has plans for improving it. He is currently looking for a way to use the handset hook to disconnect calls as well as a way to implement the rotary dial for number entry. We think that hacking a Bluetooth headset would easily take care of the first part, as well as eliminate the need for any sort of wired interface to his PC. It would also make it dead simple to use with any other Bluetooth-enabled device such as a cell phone.

We’re pretty sure he is open to implementation suggestions, so let us know what you think.

Atmega Analog Two Pack

April 5, 2011 by Kevin Dady 7 Comments

Back in February, [ProtoStack] posted a pretty good tutorial on how to do Analogue to Digital Conversion on an Atmega168. Based on a bread board, the tutorial also shows the often forgotten low pass filter on the AVCC lines to ensure an extra stable reference and an analog input connection to a simple voltage divider as a study point.

Moving on into the micro controller, the registers you’re going to need to twiddle are laid out and explained in detail. Finally you’re shown how to put it all together in a software project that outputs the analog reading onto a standard character LCD.

But hold on! There is more. Just released is a follow up to that tutorial which adds on Analogue to Digital Conversion Interrupts on an Atmega168A. So if you’re sitting there looking at an Arduino and want to know more about what’s going on under the hood, these are a good place to start.