RFID Unlocker

This is part 2 of the door openers.

After I moved out of the dorms into a house, I concluded that i needed another door opener system for my room door. However the system that I used in the dorms of pulling the handle down to unlock the door no longer worked. Additionally, I wanted to upgrade to RFID so that I did not even to have to take the card out of my wallet. The RFID board that I used in this project is a Phidgets RFID USB module (http://www.phidgets.com/products.php?category=14&product_id=1023 , I got mine for $10 from Ebay), which has a couple really nice features. First, it is USB, which means that I am not limited to older computers that have parallel ports. Second, it has an awesome driver and C# .NET module that throws a system message when a tag is read. This makes it extremely easy to just write a method that is called each time that the application 'sees' the appropriate message. Finally, the board contains 2 pins that can be controlled from an application that can put out enough power to activate a relay. I created an application that listened for the appropriate message and dealt with it that generally lived in the system tray, but also had a small interface with information about the most recent entry. To control what tags were allowed entry, I created a file that would be referenced that contained allowed tags and their respective owners. The application then logged each tag so that I could go back and see what tags were tried, if they were identified, and what the result was (opened/not opened). To handle actually opening the door, I purchased a fail-secure electronic door strike for ~$20 that, once a voltage was applied to the pins, would allow the door to simply be pushed open. I used one of the control pins on RFID board to activate a series of relays that activated the door strike, allowing the application to let the door be pushed open. Put them all together on a dedicated computer with battery backup and voila, it works. I attempted to have everything (USB data, 5v, 12v, strike activation return) go over a cat6 cable to the box to increase security, but was unable to get USB to travel over the cat6 (I read many articles on it, and think that the reason is because it already goes ~8 feet when it hits the cat6 injector, then an additional 4 feet or so over the twisted pairs, and signal degradation is just too much over that distance). In the pictures, the black USB B connector in the box that is just hanging there is left over from that attempt.