RFID tag emulation with ATtiny85
Wow, we can finally clone those read-only RFID tags with no trouble at all. This device emulates EM4102 RFID read-only tags that operate on 125kHz.
This project consists of just a few parts, literally, but the way they operate is quite ingenious. The most eye-catching thing is that ATtiny's power pins aren't even connected to power supply. Actually, there is no power supply we can pinpoint here, at all! It is powered from as little as 1V that it gets from reader's "primary" coil. Another crazy thing is that the clock of ATtiny is in sync with reader's frequency (125kHz) because tag's coil is connected directly to microcontroller's clock input pin. Read on to see how interesting things can get...