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Billy Club Texts Your Mother if you Hit Someone

Arduino GSM, arduino hacks, Art, billy club, gsm shield, weapons hacks Commenti disabilitati su Billy Club Texts Your Mother if you Hit Someone 

Mama, just killed hit a man, Put a gun against his head, Pulled my trigger, now he’s dead.
Mama, life had just begun, But now I’ve gone and thrown it all away…

This latest piece of half-art / half-prototype from one of our favorite hacker-artists [vtol] is a billy club equipped with a GSM-module. It automatically sends an SMS to your mother with the text: “Mom, I hit a man.” He calls it the Antenna:

The idea of the project is to create a device which strictly controls the cruelty of police. As all the standard methods of control are ineffective, this project suggests the maternity as the last stronghold of human kindness and responsibility.

An Arduino is equipped with a piezo sensor to detect impact, and a GSM shield takes care of the texting. It’s an interesting concept, similar to requiring police officers to wear body cameras. You can debate the practicality, but we’re always interested in hearing about weapons monitoring tech concepts. One of our favorites has always been the DNA gun from (Judge) Dredd. Did you know there was an Internet Movie Firearms Database? But we digress, check out [vtol’s] demo video:

Speaking of those body cameras — [vtol] also made an 8-bit photo gun not so long ago…

And since Bohemian Rhapsody is now stuck in your head (you’re welcome) here’s that little ditty:

Filed under: Arduino Hacks, weapons hacks

Safety warning: Arduino GSM shield may cause fires

arduino, Arduino GSM, arduino hacks, BaldEngineer, capacitor, gsm, Manganese Dioxide, News, Tantalum capacitor Commenti disabilitati su Safety warning: Arduino GSM shield may cause fires 


Be careful with those Arduino GSM cards. As [James] reports, they may turn into fire starters. One person has reported a small explosion and fire already on the Arduino forums.
Now before we go any further – You may be asking yourself who the heck [James] is, and what gives him the ability to second guess the Arduino team. Well, here is [James'] blog disclaimer:  “James is a Senior Technical Expert for Technology and Applications at KEMET Electronics, a capacitor manufacturer. The content of this post are his and in no way reflects opinions of his employer.”

Senior Technical Expert?  That’s a good enough reason for us to believe him.

[James] states the problem is a tantalum capacitor used to decouple the GSM radio power supply from the main Arduino supply.
Tantalum capacitors are great for their low ESR properties. However, they have a well known downside of getting very hot, or even exploding when stressed. It’s not the Tantalum Anode that is burning. The Manganese Dioxide used as a cathode in some Tantalum capacitors is the culprit.

It comes down to voltage rating (or more aptly, derating). The Arduino GSM shield runs at 5 volts. The designers chose a 6.3V rated capacitor. While this close of a tolerance may be good enough for some types of capacitor, it is a no-go for a Tantalum cap with Manganese Dioxide. The dielectric material in these capacitors is so thin that the stress of a reflow oven cycle causes cracks. The cracks pass leakage current, and this sets the Manganese Dioxide on the path to destruction.
What’s the solution? [James] suggests several options:

  1. Switch to a 10 volt part
  2. Switch to a safer Tantalum Polymer capacitor.

We haven’t heard anything from the Arduino team yet about this, but to be safe we’d follow [James'] advice.

Filed under: Arduino Hacks, news

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