[Ben Krasnow’s] latest project will be good for anyone who wants a complicated way to cheat on a test. He’s managed to squeeze a tiny FM radio receiver into a ballpoint pen. He also built his own bone conduction microphone to make covert listening possible. The FM radio receiver is nothing too special. It’s just an off the shelf receiver that is small enough to fit into a fatter pen. The real trick is to figure out a way to listen to the radio in a way that others won’t notice. That’s where the bone conduction microphone comes in.
A normal speaker will vibrate, changing the air pressure around us. When those changes reach our ear drums, we hear sound. A bone conduction mic takes another approach. This type of microphone must be pressed up against a bone in your skull, in this case the teeth. The speaker then vibrates against the jaw and radiates up to the cochlea in the ear. The result is a speaker that is extremely quiet unless it is pressed against your face.
Building the bone conduction mic was pretty simple. [Ben] started with a typical disk-shaped piezoelectric transducer. These devices expand and contract when an alternating current is passed through them at a high enough voltage. He cut the disk into a rectangular shape so that it would fit inside of the clicker on the ballpoint pen. He then encased it in a cylinder of epoxy.
The transducer requires a much higher voltage audio signal than the litter radio normally puts out. To remedy this problem, [Ben] wired up a small impedance matching transformer to increase the voltage. With everything in place, all [Ben] has to do to listen to the radio is chew on the end of his pen. While this technology might help a cheater pass an exam, [Ben] also notes that a less nefarious use of this technology might be to place the speaker inside of the mouthpiece of a CamelBak. This would allow a hiker to listen to music without blocking out the surrounding noise. Continue reading “Turning an Ordinary Pen into a Covert Radio Receiver”
It has been far too long since we’ve seen an installment of Retrotechtacular, and this is a great one to start back with. It’s always a treat to get the story from the horse’s mouth. How about the tale of the world’s first Digital Single-Lens Reflex camera? [Jame McGarvey] shared the story of how he developed the device in 1987.
That’s it shown above. It’s not surprising to see that the only real modification to the camera itself is the back cover. The difference between an SLR and a DSLR is really just the D, which was accomplished by adding a CCD in place of the film.
The entire story is a treat, but there are a couple of nuggets the we enjoyed most. The possibly-clandestine purpose of this device is intriguing. It was specifically designed to pass as a film camera which explains the ribbon cable connecting the CCD module to the control box which would be stored in a camera bag. It is also delightful to hear that the customer who tasked Eastman Kodak with developing the system preferred Canon camera bodies. So this Kodak DSLR indeed used a Canon F-1 body.
Once you get done looking this one over you will also enjoy learning how a CCD actually works.
Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.
Ah, the movies are an inspiration for so many projects. How many times have you seen a spy movie where a cutout in the pages of a book are hiding something? This was the inspiration which led [Paul] and his crew to try using a laser cutter to remove a handgun-shaped cutout from the pages. The fail began before the project even got started. The sacrificial book they had chosen was too thick to cut directly so they tore it in thirds for the cutting process.
The hijinks are portrayed well in the clip after the break. The infectious giggling as this first trace of the laser cuts the outline makes the video worth watching. As they try to go deeper, the success falls off rapidly. This makes for a great Fail of the Week discussion: Why can’t you cut through multiple layers of a book with a laser cutter? Is this merely a focal length issue that would be solved with a higher-end cutter or is there something else at play here. Let us know what you think by leaving a comment below.
Continue reading “Fail of the Week: Secret Agent-Style Book Hideaway”
This is the first in our series of videos meant to spread the hacking goodness far and wide on the net. As you can see, it is a pretty silly video, hopefully you enjoyed the humor. This wouldn’t be hackaday without an appropriate writeup though!
Initially the idea was to make this as a device that my boss could deploy from his Tesla Model S. Ultimately, we missed the release of SkyFall, so the whole 007 theme seemed a little flat. However, we did just happen to have a wonderful woman in the office that agreed to be an “overly attached girlfriend”. Here’s a link to the meme for those who are unfamiliar. Even though we made her look like a crazy person, she was a great sport about it (Thanks [Stephanie]!).
The Goal was to have a radio controlled device that would send live video and audio to someone and had the ability to plant a small GPS tracker on the undercarriage of a car.
Continue reading “Hacking a radio controlled spy device for overly attached girlfriend.”
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.
[Thierry Legault] doesn’t just look up at the stars, the uses a motorized telescope base of his own making to track and photograph secret objects orbiting the earth. What do we mean by ‘secret objects’? Spy stuff, of course.
Last month he captured some video of the X-37B, an unmanned and secretive reusable spacecraft (read: spy shuttle) which is operated by the United States Air Force. That was back on the 21st of May but a few nights later he also saw the USA-186, an optical reconnaissance (Keyhole) satellite.
After trying to cope with manual tracking using the RC control seen above [Thierry] set out to upgrade his equipment. He ended up designing his own software package (and then released it as freeware) to automatically track the trajectory of orbiting objects. He uses a second telescope to locate the object, then dials it in with the bigger telescope. Once in frame, the software takes over.
[Wired via Dangerous Prototypes]
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”