EMP shopping cart locker

Step 4 Recreating the locking signal (theory)

When a current flows in a wire, a magnetic field is created around it. When a lot of current flows through a wire, a large magnetic field is created around it. To a zeroth order approximation, flowing current through a loop of wire with any signal will produce a magnetic field that will induce approximately that same signal in other loops of wire - say, a shopping cart wheel.

By using a microcontroller to recreate the locking (or unlocking) signal and feeding that through a Serious Power Amplifier will allow you to broadcast that signal through the aisles of your local foodmotron or local merchandise pick-upery.

The rest of the steps will show you how to build your own Serious Power Amplifier.