It’s that time of the year again. The leaves are changing colors, it’s getting colder outside, and all the littler hackers are off to college. Which means we get to see an influx of dorm room locks and openers.

[Adam] is back at it again with a new keypad dorm room lock. Last year he had an exceptional setup using a car keyfob, so we’re a little curious as to why he would revert to such a low level system as a keypad that isn’t even color coded.

Perhaps its in his “new” way of presenting the hack. Rather than a blog or write up, he documents the entire most of the process in a little less than 20 YouTube videos. Watch him testing out the system after the jump.

[MusashiAharon's] dorm room door was practically begging to be hacked. There was already an electronic strike plate in place as well as junction boxes on the inside and out that were connected by conduit. Jumping on the bandwagon after seeing some other door lock hacks here, he built one that uses a rhythmic combination.

The control panel on the outside is a blank faceplate with two buttons and a status LED. Theses are wired to a jack and connected with a cable traveling through the conduit to a breadboard on the inside of the door. Seeing a large breadboard hanging on an outlet cover is a bit comical but it does the job. From there, a Teensy microcontroller waits for the code and if correct, actuates the strike plate via a relay.

The rhythmic nature of this lock reminds us of the knock-based system. One button signals the start and end of the code, the other is used to input the rhythmic sequence. This does seem a little more discreet and we’d imagine it’s quite hard to eavesdrop on the correct combination.

It seems like creating an automatic dorm room door opener is a rite-of-geek-passage each fall. [Adam], a student at Vassar, passed with flying colors by creating this clean setup. We’ve got video, more pictures, and a description after the break.

Above we see the device mounted on the inside of the door. The larger box houses a printer head carriage that does the physical turning of the handle. When the carriage moves from right to left it pulls a string attached to a long lever on the door handle (seen in the picture at the top of the post), providing the turning motion. Below this box is the control circuitry that we’ll look at next.

Here we have the brains of the operation. In the project box on the left is a board that takes care of the wireless fob communications. [Adam] tells us this works from about 250′, uses a roll algorithm over RF for security, and has a dedicated 12v DC power supply. In the middle is the timer circuit that controls the motor operation, with four 9v batteries providing the motor with power.

Motor control is provided by a timing circuit using three 555 timer ICs. [Adam] based his design off of a two chip delay circuit but scaled it up to three to give him more options. The circuit is responsible for driving the motor until the latch is open, holding for a set amount of time, then returning the motor to its original position.

Because he’ll be moving out at the end of the year, [Adam] wanted to make the system easily transportable. He’s used a jack system so that the controller can be mounted either above or below the motor unit at his next residence.

This works well and with the covers on the project boxes it’s not the duct-tape mess of the last door opener we saw. Nice work!

[Chris] wrote in to tell us about this project he did while living in the dorms. He built a system to automate his dorm room door. It handles unlocking and opening/closing the door via iPhone, secret knock, and even the key.  The lock/knob portion is handled by a servo while the opening/closing action is hydraulic. After living with it for a year, he says that it never gets old, but there were a few bugs. Apparently it would randomly open in the middle of the night sometimes. If you’re interested in doing something like this, but not damaging the door, maybe you should check out the RFID dorm door lock project.

[Max] sent us his dorm room RFID controlled lock. While RFID door locks are nothing new, his implementation is very slick. The entire unit is attached with suction cups to a mirror on the inside of the door. It looks like it could be removed and put elsewhere in a matter of seconds. That’s pretty slick. Much cleaner than the touch sensitive dorm lock we saw last year.