MIT students Grant Jordan and Kyle Vogt found themselves in possession of a high-security safe -- the S&G 8400, a class-1 safe of the sort formerly used to store classified documents. They wanted to open it, but they lacked the combination and were unable to crack it using the sort of techniques that work on lesser strongboxen. So they build a safecracking robot that autodialled combination after combination (the robot excluded "impossible" combinations that couldn't be set due to material limitations of the mechanism, which substantially reduced the keyspace). They eventually opened the safe, but didn't find anything interesting in it.
We used a custom stepper motor to rotate the dialer head. The dialer head transmits torque to the dial via a piece of heavy duty surgical tubing. The stepper motor we chose has more than enough resolution to implement our algorithm, but it's not quite as fast as it could be. Stepper motors have an extremely high "holding torque", which is ideal in this situation since the dial must be held in place while the butterfly knob is being turned.
The head also contains an RC servo motor with a machined knob to mesh with the butterfly knob. This setup enables independent rotation of both the dial and butterfly knob. The stepper motor shaft is also connected to a high resolution optical encoder for position feedback. The encoder is mainly used to detect when safe is successfully opened. The torque required to open the safe when the correct combination is entered is much higher than the maximum torque of the stepper motor, so the encoder is programmed to report when the position error exceeds a certain threshold. Basically, the stepper motor stalls and the encoder flips out if the safe actually opens.
This handheld magnifying glass has two bright LEDs and is powered by 3 AAA cells (not included). The manufacturer says the magnification is 40X. I think it is less than that, but it is still plenty powerful for my needs – mainly, reading the markings on tiny electrical components and checking the layer fusion on […]
The curved bottom of the cup peeks through your drink as the level drops down, moving the “moon” from full to a fingernail-paring sliver. Of course, it works better if you drink something cloudy and white — it’s designed some cloudy Korean rice-wines, but would also work with Pernod and water, I’m thinking.
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Power up your gadgets in the most unexpected places with the extremely compact SolarJuice battery pack. SolarJuice charges up at home like your average battery pack, but also lets you add extra juice on-the-go using its built-in solar panel—so you’ll never be left unplugged from the digital world.4.5 Stars on Amazon!Simultaneously charges 2 devices at […]