Turning an Ordinary Pen into a Covert Radio Receiver

[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”

Board lets you know when to hold ‘em; know when to fold ‘em

Don’t mind me, I’m just listening to some tunes during our poker game. Well, that and getting some electronic coaching about poker odds. This board lets you wiggle your toes to input the upcards, and those in your hand. After each entry the gadget will tell you your odds of winning the hand. Take it easy with this kind of stuff, if Rounders was at all realistic, getting caught cheating is a painful mistake.

The thing we find interesting about the system is that it doesn’t use a stored odds database. Instead, the Propeller chip runs a simulation of 1000 hands of poker based on the cards you have entered and uses the results to calculate the odds. [Nick] says that this runs quickly because he’s using multiple cores for the calculations, and it cuts down on the data that the device needs to have on board. Right now the feedback uses a text-to-speech generated voice, but you can customize the audio clips if you’d like. Check out a demo of the device in the clip after the break.

Not looking to get the beat down for cheating? Here’s a poker tournament timer that we assure you is on the up-and-up. Continue reading “Board lets you know when to hold ‘em; know when to fold ‘em”

High school students hacking electronic tests

[Alex Papadimoulis] wrote about ingenuity and hacking in high school. Immediately after the teacher’s installed a new electronic note taking and test giving software, the students began hacking. They managed to find several ways to ace their tests, none of which involved studying hard the night before. Ultimately, the teachers went back to the old system to prevent such shenanigans.

[photo: COCOEN]