Electromagnetic Bike Shed Lock @Raspberry_Pi #PiDay #RaspberryPi
from KingD29 via Instructables
When everything is running and powered on, you take the rfid card and scan it on the rfid reader. The lock is automaticly open and upon card scanning, the lock will close. when you meanwhile try to scan with another badge, this will not work because it is another than the one that last checked in to store his bike.
When you scan with the card again that was used the first time, the lock will open again, and you are free to take your bike back home.
