The aerial for the card can now be accessed near the right hand end of the signature strip.

Carefully scrape away the plastic here. Dripping on acetone (nail polish remover) will soften the plastic

Eventually you will uncover some thin wires (click on image for larger version)

Older cards

The aerial for the card can be accessed under the word "Sign" of "Sign your name here"

Carefully scrape away the plastic here. Dripping on acetone (nail polish remover) will soften the plastic

Eventually you will uncover five thin wires (click on image for larger version)

Break these wires

Enjoy your non-broadcasting debit-card