Parabolic microphones are used to listen in from a distance. You see them on the sidelines of NFL football games, but they’re part of the standard issue in detective and spy novels. Now you can build your own parabolic microphone by following this example.
The one component that may be hard to find is the parabolic reflector. You cannot simply use a bowl or other curved object as the precise parabolic shape ensures that sound waves are reflected onto one finite focal point. For this build the reflector was obtained from an eBay seller. But the other parts are scavenged from easy to find sources. The microphone itself is an inexpensive element from Radioshack. It is mounted in the shell from a tweeter speaker, which helps to gather the sound if the element isn’t exactly aligned with the focal point. The setup also needs a preamplification system, which uses many components. Luckily there’s a schematic and other reference material linked in the write up.
You can also build a laser microphone which detects sound waves on a pane of glass.
[Sulaiman Habsi] and two classmates put together a Morse Code interpreter as a class project at Sultan Qaboos University. The system listens to a morse code signal using a microphone, then translates that input to text which is displayed on this character LCD.
The breadboarded circuit feeds an audio signal from the microphone, through an OpAmp, to the ADC of an ATmega8 microcontroller. The captured signal is stored as a byte in a special way. The three least-significant bits signify how many total dots or dashes are contained in the character, the remaining bits represent those dots and dashes with zeros and ones. A full description of this process is included in a PDF linked in the article above. As you can see in the video after the break, the hardware waits to process all of the signals once the full message has been received.
This would be a great add-on for a Morse Code practice keyer.
Continue reading “Morse Code interpreter”
[Mnt] wrote in to tell us about this 360 degree array of cameras featured on [Codeninja]. This has to be one of the most impressive arrays of cameras and sound equipment that we’ve seen at Hack a day.
The array is capable of 360 degree x 140 degree panoramic views using the 9 cameras arranged in a circle around the base. Impressive in itself, these cameras are all capable of both pan and tilt rotation via and Arduino-controlled servo setup. It also has a native 360 degree camera mounted on top of everything for calibration purposes and IR-LED illumination capabilities.
On top of all of this, the camera array also features audio capability with a 9-microphone setup, presumably one for each camera. This, coupled with piezoelectric speakers should provide for echolocation capability. Although jokingly called the “Schäuble Jr.” after a German politician, we’re not sure of the true purpose for this “sensor array.” We can only hope that it will be used for good. A very impressive build, it will be interesting to see what comes of it.
We saw this one a few days ago when it was first bouncing around the interwebs but never took a close look at it. Today, when we ran across a direct link in the tips box it was the promo video (embedded after the break) that won us over. Once you dig into the particulars of The Verbalizer we think you’ll agree that this is a hackable conference badge without the pesky need to attend a conference.
As you probably guessed from the design of the PCB, this is a microphone. It’s intended for use with Google’s new voice search feature, and connects to a computer via a Bluetooth module. But really it’s just another roll-your-own Arduino with a few extra bits. You’ll find an ATmega328 and an FTDI chip which provides a USB connection for programming. The real fun starts with the microphone and speaker circuitry which is just waiting to be breadboarded at home. We found a few other things while poking around in the schematic (available by downloading their Product Docs and Schematics package). It looks like there’s some capacitive touch… you what? Isn’t it more fun if you find this stuff yourself, kind of like the hidden gems of the DEFCON badges?
Continue reading “A badge without a conference”
Like most other DSLR cameras that feature video recording, the Canon T1i has a small built-in microphone with limited sound reproduction capabilities. [Robb] wanted better audio performance while taking video, but found the camera’s inability to use an external microphone to be a frustrating limitation. He decided to take matters into his own hands, and disassembled his camera in order to add an external microphone jack. The process is not overly complicated, as it requires little more than the installation of a switching microphone jack. You will however need to get your hands a bit dirty since it involves opening the camera, a bit of drilling, and some epoxy. Doing such things to your camera clearly voids the warranty, and with a $600 camera at stake, this hack is definitely not for the faint of heart. That said, if you desperately want to get better quality audio from your Canon T1i or 500d DSLR, be sure to check out his tutorial.
Here is a low component count FM transmitter. It sacrifices some features, like the ability to adjust the frequency, for simplicity’s sake. The build method is fairly common with amateur radio but we don’t see it around here too much. Each component gets a 5mm-by-5mm copper clad pad which is super glued to the ground plate as an insulator. There’s even a pictorial example of this method if you need some help with visualization.
One of the schematics included in the article shows how to incorporate a condenser microphone into the unit. We guess that makes it pretty easy to add an FM ‘bug’ to your arsenal of covert listening devices. Just make sure to check your local laws before building and using this. We’re not sure what the FCC would think of it here in America so we’re hoping some well-informed readers will educate us with a comment.
Here’s a surprisly simple way to build yourself a laser-based listening device. It consists of two modules, a transmitter and a receiver. The transmitter is a set of lasers, one is visible red for aiming, and the other is infrared for measuring the vibration of a surface. Point the transmitter at the window of the room you want to listen in on and the laser can be reflected back to the receiver. The receiver module has a phototransistor to pick up the infrared laser light, and an LM386 audio amplifier to generate the audio signal sent to a pair of headphone. The need to be well-aligned which is easy enough using a pair of tripods. Check out the demo after the break.
Looking for something to do with the leftover laser diodes from this project? Try making yourself a laser microscope.
Continue reading “Laser mic makes eavesdropping remarkably simple”