N and V column

Column #120: You Can’t Touch That: Non-contact Access Control
Page 62 • The Nuts and Volts of BASIC Stamps (Volume 6)
There are two essential components in an RFID system: a transceiver (reader) and a
transponder (tag). If it were only that simple.... Tags can be active (contain their own power
source) or be passive (create parasitic power from the reader's RF field). Further, tags can be
read-only or read-write. Zoiks. Let's just keep things simple, shall we?
Parallax worked with world-famous hardware hacker and engineer-extraordinaire, Joe Grand
(owner of Grand Idea Studio), to create a low-cost RFID reader that would be simple to use in
hobbyist and professional projects. The result is a fully integrated reader PCB that contains
the required circuitry and matched antenna to work with passive, read-only RFID tags. Note
that the reader is specifically designed for tags that contain low-frequency (125 kHz) RFID
components from EM Microelectronic. Parallax carries a couple tag types (disc and ISO
card) that are manufactured by Sokymat and that meet the requirements of the reader. Figure
120.1 shows a few sample tags from Sokymat that I played with; you can clearly see the disc
(far left) and ISO card (far right) tags.
Figure 120.1: Various Sokymat RFID Tags sold by Parallax