Someone already wrote a program and made a simple instruction for building the hardware that lets you read every type except for the "Avid Encrypted" tags, which can be read but not decrypted. They also put a web API online for decrypting the Avid Encrypted tags and they have instructions for how to build your own decryptor. Everything is here.
Standards and "Standards"
All chips operate at either 125 kHz (ISO) or 134.2 kHz (proprietary) but a scanner using either frequency can read both types:
Although ISO chips are optimized for 134.2 kHz, in practice they are readable at 125 kHz and the "125 kHz" chips are readable at 134.2 kHz.
-- from this section on wikipedia
ISO 11784 & 11785
Includes half-duplex (HDX) and full-duplex (FDX) types. I've seen references to FDX-A and FDX-B but unsure of the difference.
Readers retail for ~$150 on ebay.
Also known as Trovan Unique. Also used by some HomeAgain chips and Bayer chips.
FECAVA / Destron
- Avid EuroChip
- Original HomeAgain chip
Also known as Avid Encrypted.