In early 2006, Wiley published RFID Toys: 11 Cool Projects for Home, Office and Entertainment as part of its ExtremeTech series. The deal itself arrived sideways: during the first media storm in 2005, a caller stopped halfway through what I thought was an interview and admitted, "I'm not really interviewing you." He worked for Wiley, and they wanted a book of RFID projects from the guy with the chips in his hands.
Their terms were bracing. They wanted 15 to 20 projects, written start to finish in three months. I had been working with RFID for all of 45 days at that point. I countered with five or six months; they sent a $10,000 advance and said past six months the project was off and the money came back. We negotiated the project count down to 11. In truth I managed nine and padded the rest with chapters that had interesting content but no builds. The subtitle stayed at 11.
Chapter 5, the fire safe, nearly broke me. Research time was so short I stood in the store aisle cracking open display safes with the tools in my back pocket (the clerks were not amused) until I found one whose pin-pad lock was driven by a simple solenoid. The hack rode the LCD backlight signal through a transistor to power the RFID reader. It worked, I photographed everything, wrote the chapter... and then it stopped working. The culprit: fresh-from-the-package batteries had settled to their normal output, and the solenoid's draw sagged the supply enough to kill the reader mid-unlock. From outside, just a click and a clack. I tore it all down, split the voltage with a series resistor, and documented a second push-button variant for good measure.
The motorcycle chapter fared better: a smart RFID reader and relays tucked into my '05 Hayabusa, wired in parallel with the key, so either the key or my implant starts it. That build later grew a wiring diagram for GSXR riders, and in 2007 Matt Trossen of Trossen Robotics began selling RFID Toys parts kits at ThinkGeek.
The ledger, for the record: the book barely broke its advance before going out of print, and I lost money writing it. Worth it anyway. My favorite part is still the hardware appendix: what everything is, where to get it, what it costs, written so readers could dream up their own projects instead of copying mine.