Anti-theft shopping cart wheels are at a frequency that can be played by an MP3 player using a simple wire antenna that plugs into the headphone jack. For thos

Anti-theft shopping cart wheels are at a frequency that can be played by an MP3 player using a simple wire antenna that plugs into the headphone jack. For those of you following along at home, a friend of mine posted this a while back: http://zpriddy.com/2010/07/13/wal-mart-shopping-cart-locker/ http://zpriddy.com/2010/07/13/wal-mart-shopping-cart-locker/