Using A Theremin For Medical Applications

September 17, 2014 by Mathieu Stephan 30 Comments

[Eswar] is not an ordinary 16 years old boy. He figured out a noninvasive way to measure breathing in hospitals for less than $50. He is using a theremin to measure the rise and fall of a patient’s chest. For our curious readers, this touch-less instrument was invented back in 1929 by the Russian inventor [Leon Theremin]. It uses the heterodyne principle and two oscillators to generate an audio signal. One electronic oscillator creates an inaudible high pitch tone while another variable oscillator is changed by adding capacitance to an antenna.

As you can guess the space between the patient’s chest and the antennas placed around the bed forms a tiny capacitor which varies when exhaling. With three simple TTL chips and a little guessing [Eswar] had a working prototype ready to be implemented in the real world. If you’re interested in theremin, we invite you to see one of our previous articles on how to make one in a few minutes with a soda can.

Sweet Guitar Practice Amp Is A Literal Work Of Art

September 13, 2014 by Rich Bremer 19 Comments

Check out this ~~odd~~ different looking guitar practice amp. It looks like a professionally manufactured product but it certainly is not. [Bradley] made it himself, not just a little bit of it either, all of it.

One of the first things you notice is the quilted maple wood grain of the case. There is no veneer here, this started out as a solid maple block. The front radius was shaped and the recesses for the control knobs and input jack were bored out using a forstner bit. The case was sanded smooth and several coats of high gloss tung oil was rubbed on to give the wood a perfect finish. A small piece of grill cloth protects the speaker while adding a little more class to the amp. The bottom of the case is actually a cover for a computer hard drive. A rectangular hole cut in the hard drive cover makes way for a 9 volt battery compartment.

There are two control potentiometers, one for volume and one for gain. Any old knobs wouldn’t do for this project. [Bradley] knurled and turned his own aluminum knobs and they look awesome! The units power is turned on when the guitar cord is plugged in. An LED not only indicates that the power is on but it also gets brighter with the volume input from the guitar. The LED also pulses if two strings are out of tune with each other giving the guitarist an opportunity to tune one of the strings until the LED stops pulsing. When it is time for some private jamming headphones can be plugged into the amp and doing so cuts power to the speaker.

The electronic circuitry is [Bradley’s] design also, but unfortunately he doesn’t share the schematic. I suppose he wants to keep his amp one-of-a-kind.

Pro-Quality Pickup Winder You Can Make At Home

September 12, 2014 by Rich Bremer 24 Comments

A lot of people find the art of building a guitar to be a worth while and pleasurable hobby. The task can be as easy as buying pre-made parts and assembling the guitar or as complicated as starting with just a piece of wood. Even advanced guitar builders normally do not get involved enough to wind their own pickups as it can be a tedious and labor intensive task. A low-end professional pickup winder can be purchased for about $450 which is certainly not economical for the hobbyist. [Doug] is one of those folks that wanted a pickup winder but didn’t want to shell out the big bucks. So what did he do? Build his own, of course.

If [Doug] was going to build a winder he was going to do it right, with all the features to make pickup winding as quick and painless as possible. The winder needed to be fast, count the windings and stop after a pre-programmed amount of revolutions. To keep this machine safe and reliable while maintaining the ability to spin quickly, [Doug] chose to base the machine on an off-the-shelf wood lathe since they are sturdy and made to spin at high speeds. The lathe is equipped with a face plate where the pickup is mounted.

Once the pickup is mounted to the face plate, the desired amount of turns is programmed into a digital counter that receives a signal from an opto switch and encoder disk attached to the lathe spindle. The motor speed is manually controlled by a user-adjustable potentiometer. There is also a stand alone tachometer that gives speed feedback to the user. Once the counter reaches the pre-programmed limit, it trips a relay that cuts power to the motor. This way the amount of windings can be precisely controlled. There is even a switch that changes the motor direction for reverse winding humbuckers without the need to remove and flip over the pickup.

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Let The Bass Cannon Kick It!!

September 7, 2014 by Matt Terndrup 51 Comments

If you’ve ever found yourself immersed in the wild realm of electronic dance music, then chances are you’ve probably heard [Flux Pavilion]’s dubstep banger ‘Bass Cannon.’ The music video released for the track shows [Flux] and his minion [Doctor P] performing twisted audio experiments on unexpecting research candidates by blasting them in the face with strong waves of sound vibrations, which blew back the hair of the people strapped to the chair. The audio trials took place inside what looks to be a warehouse filled to the brim with speakers, heavy duty subs, and sound boards; making it more like a ‘room of bass’ rather than a bass cannon itself. Yet, it inspired one of Hackaday’s Alum to literally create a bass cannon himself. And as you can see in the video below, his device packs quite a punch.

Most of us know [Adam Munich] as the guy who built this portable x-ray machine that could look through just about anything. He’s also built a nuclear bomb detector and has documented several radiation safety techniques, but every once in a while he decides to make something utterly ridiculous like this! He describes his homemade bass cannon as having a variety of fun and exciting uses including a mobile party on one’s shoulders, a way to frizz your hair, or an electrifying method to scare the neighbors.

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Extrinsic Motivation: An Open, Modular Effects Pedal

September 4, 2014 by Brian Benchoff 18 Comments

Microcontrollers and Arduinos are cool and all, but dealing only in the digital domain does have its limitations. In fact, most of your electron heroes didn’t begin their electronics career by blinking pins on digital outputs; they were solely in the analog domain with their radios and, yes, guitar effects pedals.

[Josh]’s entry for The Hackaday Prize was by far the most analog project of the entire contest. It’s an open source effects pedal that takes advantage of the modular design of the most popular pedals in history.

A good number of the famous circuits for turning an electric guitar into an aural experimentation are based on small circuit modules, packaged and repackaged again until the desired tone is achieved. [Josh] wants to pack these modules separately on different boards, specifically shields, although no Arduino is used, so any sound can be created.

Already [Josh] has done some research to determine what circuits and circuit modules to clone. The list should be fairly familiar to anyone with a pedalboard – Tube Screamers, Fuzz Faces, Big Muffs, and Phase 90s are at the top of the list. He may not get to the complicated digital effects like pitch shifters and digital delays, but it’s still a great project for experimentation.

You can see [Josh]’s project video below.

This project is an official entry to The Hackaday Prize that sadly didn’t make the quarterfinal selection. It’s still a great project, and worthy of a Hackaday post on its own.

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Gemma-Powered NeoPixel Sound Reactive Drums

August 26, 2014 by Matt Terndrup 8 Comments

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This tutorial from Adafruit shows how to create a custom interactive drum set that lights up with sound. It uses a mic amp sensor that is connected to a miniature Arduino Gemma board to detect when the instrument is being hit by the sticks. Neopixels then illuminate into a range of colors creating a beautifully synced up music presentation.

The container that houses the electronics is 3D printed. The entire circuit is integrated into the snare, mid-tom, hi-tom and a drum kick. All the code and step-by-step instructions can be found on Adafruit’s website. Now imagine something like this being packed up in a suitcase and carried from venue to venue as an up-and-coming band travels from state to state on tour; especially at Drum n’ Bass raves or electronic based music festivals. A video of the kit being used is below.

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An IPod Dock Converted Into Chromecast Speakers

August 26, 2014 by Matt Terndrup 13 Comments

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[easybakejake] figured out a way to fuse together an iPod speaker dock and a wireless Chromecast receiver. His method utilized a modified HDMI-to-VGA adapter. From the looks of it, apps like music for Google Play, Pandora, and Music All Access seem to able to be streamed through this device.

A few problems did come up with this project though when researching the functionality of this music hack. For one, there is little to no documentation since the tip came to us through a Reddit post. Another inconvenience had to do with supporting different monitor sizes. [easybakejake] confirmed in the comments of that post that he ran into an error where the input was not working; probably due to a resolution issue. Eventually, he got it working and dubbed the device the MusicBox. Now stick it on a roomba and get it to DJ a party (like this Parks and Recreation skit that follows after the break):

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