Fobs used for “access control” (access to a given area) are electronic keys as fobs, which are used for controlling access to buildings or even vehicles. Fobs used to be used just as keychain accessories. These new fobs come in two types: the type that broadcasts a signal over a very limited range at all times (passive), and the type that has a button which transmits the signal (active). You can tell the difference based on whether or not your fob has a button. Passive fobs can even be programmed to only allow access during different times of day, or different days of the week, but your condo fob is not programmed with that capability.
Early electric “key fobs” use infrared light so a clear line-of-sight between the fob and the reader was necessary to gain access to the building the fob was for. These infrared fobs were expensive but could be copied using a programmable remote control device. Someone with the device could copy a fob rather easily. Newer key fobs RFID (Radio Frequency Identification), so these RFID fob models are harder to copy. More importantly, they function without line-of-sight, meaning you can have the fob in your pocket and stand next to the reader and it should work.
RFID key fobs can be easily duplicated with both homemade gadgets and tools you can buy online. Fob Copy is one of a number of companies who offer this service.
How Fobs Are Made
There are many different key fob manufacturers around the world but fobs are manufactured pretty much the same way everywhere: a plastic shell is created to house the chip, then the chip is inserted into the shell.
Programming the Tag
First, the chip (or tag) has to be programmed, and this programming is done on a large scale at factories. There are two main types of tag programming:
- write-once, read-multiple
- write-multiple, read-multiple.
Write-once tags are tags that can only be imprinted once. So once they have an RFID imprinted on them, they can never be used again.
But many condo fobs are “write-multiple” and can be rewritten. For example, if you have two fobs and you lost one, your building may choose to rewrite your remaining fob and then copy it, rather than issue new ones. (If your fob is write-once, this is not an option.)
Making the Fob
The fob itself is manufactured on an assembly line, with the tag being inserted between two pieces of plastic and then the plastic sealed:
Some newer fobs have the tag housed in two shells, so that there is less of a chance of damaging the chip or tag.
That’s all there is to it. If you are handy enough you can probably make your own fob for an RFID tag. What you would use it for we can only guess.