No secret knocks required at [Steve’s] house – your subway pass will do


[Steve] is often host to all sorts of guests, and he was looking for an easy way to let his friends come and go as they please. After discovering that his front door came equipped with an electronic strike, he decided that an RFID reader would be a great means of controlling who was let in, and when.

Giving all your friends RFID cards and actually expecting that they carry them is a bit of a stretch, but lucky for [Steve] he lives near Boston, so the MBTA has him covered. Just about everyone in town has an RFID subway pass, which pretty much guarantees that [Steve’s] cohorts will be carrying one when they swing by.

He crafted a stylish set of wooden boxes to contain both the RFID reader and the Arduino that controls the system, matching them to the Victorian styling of his home. A single button can control the setup, allowing him to add and remove cards from access lists without much fuss. For more granular control however, [Steve] can always tweak settings from the Arduino serial console.

The card system is both stylish and useful – a combination that’s hard to beat.

Garage door opener now a bedroom door closer

[Roy] had an extra garage door opener on hand and decided to put it to use as a remote control closing mechanism for his bedroom door. We gather he has some noisy housemates as the inspiration for the project came from not wanting to get out of bed to close the door when the ruckus interrupts his TV watching.

The image above shows the hinged system which translates the linear motion from the garage opener track to the rotational force necessary to swing the door closed. We’d say he really nailed it because the system matches the angle of the door jamb perfectly, and when the door is fully open the angle bracket is almost flat against the wall. We certainly don’t have the same need for closing doors, but the mechanism is something to keep in mind.

The motor for the opener is hidden beneath his desk. You won’t be able to see it in the video after the break because he built a matching enclosure around it. Now he just needs to add some WiFi connectivity and he can ditch the uni-tasking RF remote for a smart phone app.

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Chicken coop door using threaded rod

There’s no rooster to wake them up, and [Steve] and his wife are fine with that. What they’re not fine with is having to get up early anyway in order to let the chickens out of the coop. Like many small-scale egg farmers they sought out an automatic solution for opening the coup in the morning.

[Steve] had seen a bunch of different automatic coup door hacks kicking around the Internet. But all of the ones he could find used a vertical door and pulleys. His setup has a door that opens horizontally and he realized that he needed to build some kind of linear actuator. What he came up with is a system built with hardware store parts. He’s using a plain old piece of threaded rod along with a coupling nut (they’re usually 3/4″ long or so). The nut is held firmly on the door using a conduit mounting bracket, while the threaded rod is turned by an electric screwdriver mounted to the jamb. Two limiting switches are made up of magnetic sensors often used to ring the door entry bell when you enter a store. An Arduino takes care of scheduling and controlling the motor for opening and closing the door. See for yourself in the high-production-value video after the break.

For what it’s worth, we have seen at least one rope and pulley door that slides horizontally.

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Apartment entry morse-code lock

[Bozar88] lives in an apartment building that has a buzzer at the front security door. Guests find your name on the panel next to that door, and press a button to ring the phone just inside the entry of each apartment unit. He decided to extend the built-in capabilities by adding a morse-code entry password which unlocks the security entrance automatically (translated).

He designed a circuit and etched his own board which fits nicely inside of the wall-mounted phone. It uses an ATtiny2313 to implement the coding functions. The device attaches to the intercom line in order to detect incoming button presses from the entry panel. There’s some protection here to keep the signal at or below 5V. The output is two-fold. The microcontroller can drive the microphone line using a transistor, which gives the user audio feedback when the code is entered. To unlock the door an opt-isolated triac (all in one package) makes the connection to actuate the electronic strike on the entry door.

The video after the break is not in English, but it’s still quite easy to understand what is being demonstrated.

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Your theme song greets you at the front door

One thing you can look forward to when arriving at home after a long, arduous day at the office is some peppy theme music when you walk in the door. [Sebastian Sommer] built the system, and shows it off in the video after the break by dancing to James Brown’s I feel good.

The setup uses an Arduino as a microcontroller. It monitors a hall effect sensor on the jamb which detects a passing magnet on the door. We guess this means the system doesn’t know if you’re coming or going but perhaps a future upgrade would add an infrared beam to detect your legs as head out the door. The music itself is played by an SparkFun MP3 shield which has a decoder chip, microSD slot, and audio jack for the powered speakers. [Sebastian] grabbed a copy of [Bill Porter’s] mp3 shield library to get the project up and running quickly.

This is a pretty cool addition if you’re already using an Arduino for a door lock or vice versa. Or maybe you’re not home enough to make this hack worth it, in which case you simply must take this music playing Tesla coil hat along on your commute.

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Geared system adds RFID to regular door locks

[Flowolf] added an auto-locking RFID entry system to his front door. He used our favorite fabrication system, acrylic and threaded rod (we also like to throw in aluminum angle bracket from time to time). The support structure mounts underneath the escutcheon plate for the lockset, keeping the main acrylic sheet flat against the door.

An RFID reader and Arduino run the system, with a button inside to unlock the door. But if power were to fail, you will still be able to get in or out manually. When you are using the electronic system, a stepper motor connected to the geared lock knob by a chain is what grants access, then revokes it again five seconds later. The wire going up out of the this image is for a switch that lets the unit sense when the door is closed.

As shown in the video after the break, you can turn the auto-lock feature off. But we’d like to see an emergency entry feature, like a knock-based lock, because eventually you will leave without your keys!

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Star Trek style pneumatic doors that don’t require a stagehand

In 1966, [Gene Roddenberry] introduced fully manual doors powered by a stagehand on Star Trek. The fwoosh sound of the door was later dubbed into each show, but progress marches on, and now [Alex] created his own Star Trek-style automatic doors for his house.

The build includes a ‘control panel’, and [Alex]’s door operates in three modes: Open, and stay open; Close, and stay closed; and Automatic. The control panel itself is fairly remarkable. A small puck interacts with a magnetometer underneath [Alex]’s counter. If the puck is pointed towards ‘Open’, the door stays open. If the door is pointed towards ‘Closed’, the door stays closed. If the puck isn’t near the magnetometer, the door operates in automatic mode with the help of a few IR sensors to detect someone trying to get in or out of [Alex]’s kitchen.

For the mechanical portion of the build, [Alex] used a One meter long piston with the quietest air compressor he could find. We can’t tell from the video after the break if the compressor ever kicks in, but [Alex] says it’s about the same volume as his fridge. As a small added bonus, the new automatic door does have a fwoosh sound, just like [Gene] would have wanted.

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