title: How does Duff's device work?
body: <p>I've read the <a href="http://en.wikipedia.org/wiki/Duff%27s_device" rel="noreferrer">article on Wikipedia on the Duff's device</a>, and I don't get it. I am really interested, but I've read the explanation there a couple of times and I still don't get it how the Duff's device works.</p>
  
  <p>What would a more detailed explanation be?</p>