The RFID Door Lock was probably the third project I built using an Arduino, after the "flashing LED" and a simple temperature sensor.
We live in an apartment building which already uses RFID cards for building and lift access, so it would be great if we can use the same card to get into the building and also to open our door.
This project uses a commonly available 125 KHz RFID reader and cards, although other readers can be substituted.
For more detail, see:
This PCB is available for purchase at my online shop.