Modding High-end pet door
1) Read/activate via a small RFID tag instead of the very large (for a cat) sonic transmitter. The cat is feral (we lock him at night in the garage), so he sometimes gets in fights and loses his entire collar. The transmitters are $40 each! He's lost three so far.
2) Switch mode to "in only" at a preset time very night and "in and out" mode every morning.
I like the features of this door, and it's already installed. It's extremely weatherproof and resilient. Most Lexan/acrylic cat flaps I've seen or owned aren't even in the same league as this one, which is why I would prefer to keep this door as opposed to modding a different brand of door.
I know how to solder and have a very basic understanding of electronics. I could probably muddle through a DIY, but I'm not even sure it can be done. Is it as simple as locating the receiver on the board and replacing it with an RFID reader? Or is that wishful thinking? Thanks in advance for any insight, advice, help. :)