Arduino Entry system using 12VAC doorbell trafo
Posted: Tue Aug 31, 2010 11:42 am
Hi! Enticed by an interst for home automation and electronics (of which I have limited experience) I recently started a small project. I own a house and rent out the second floor. The tenants and my family share a common entrance door, requiring a lot of keys. Reading about the arduino I started to think about a keyless entrysystem and the possibility of providing a upgraded doorbell and VFD status display at the front door. I also want to incorporate magnetic switches to monitor door status for all three doors (basement, our entrance door and the front door shared with the tenants).
Luckily my house is equipped with an ancient doorbell transformator, deliviering approximately 12 volt ac through surface mounted wiring to two old doorbells. Powering the arduino with this powersource should make for a clean setup without wallwarts, and also be able to provide power for a magnetic doorlock. The rough sketch of what I want to accomplish is as follows: A nice, clean aluminium plaque at the front door, providing bell buttons for my family, a separate button for my kids and one for the tenants. I chopped a old htpc case (Antec Mozart) for a nice 16x2 VFD display and the aluminium plaque with a display window. VFD is a necessity here, outdoor temperatures commonly drop to -25 degrees C (or colder), so no LCD would reliably work here. The VFD also has bright blue characters, perfect for those dark, gloomy winter nights.
I have purchased a few magnetic door contacts (http://www.clasohlson.no/Product/Produc ... d=55369098). A little experimenting with kaku magnetic door sensors left me disappointed. I do not want to surface mount ugly, expensive sensors and accept the lessened reliability of radio communication and battery changes, so i drilled a couple of holes in the doorframes in order to install these switches. They are practically invisible and work 100 % reliably. These will be wired to the arduino using a resistor ladder, thereby only requiring 1 pin and also giving me the possibility of monitoring a broken or cut wire.
In addition i have bought a pressure sensitive mat (http://www.clasohlson.no/Product/Produc ... =152538724), this will for now reside under the doormat at my familys entrance door, but later i will put it under my new wooden floor when i redo the hallway. This should provide the arduino with enough information to reliably estimate if someone is leaving or coming (door opens/pressure detected vs pressure detected/door opens), and display appropriate information on the VFD (house armed/disarmed, doors/widows open, turn on lights etc).
Today i ordered a simple RFID reader (TTL) and an antennae that should fit behind the plaque perfectly. Still on the buying list is a magnetic door lock for the front door.
My plan is to pull wiring from the front door and the sensors to a indoor arduino with a LCD display. i will run 12v to the front door and to the arduino situated next to our entrancedoor, and a network cable containing leads for the VFD, doorbells and sensors beetween the two doors. I should be able to see status of all doors, keep a small log of doorbell and door activity, and open the door with a switch. I have purchased a arduino network shield in order to forward all this information to my domotiga server (and possibly be able to open front door with sms or a web interface for kids, carpenters and my wife who forgets easily but is not easily forgotten)
Being a big project for me, I have started out with a simple doorbell. My arduino is now powered through the 12v ac using a home made circuit with a diode bridge, a couple of capacitators and a 5v voltage regulating IC. The exisiting doorbell wiring is hooked up to a optocoupler trough a diode bridge, capacitors and a resistor. When my doorbell is pushed, my arduino plays the Mario theme to the amusement of my kids (always entertain the masses if u need massive support). A SAE 800 tone generator was tried, but it's reassuring "ding-dang-dong" did not receive support, so we're sticking with mario.
Currently im hacking away in order to get the aluminium panel ready and all buttons installed. Using a small motion detector (https://www.elfa.se/elfa3~eu_en/elfa/init.do?toc=20135) to turn on/off the outdoor vfd (and log more data) is an option, but that will be put on hold for now. Hopefully I'll locate my camera one of these days and take some pictures and eventually provide you with schematics and code.
Luckily my house is equipped with an ancient doorbell transformator, deliviering approximately 12 volt ac through surface mounted wiring to two old doorbells. Powering the arduino with this powersource should make for a clean setup without wallwarts, and also be able to provide power for a magnetic doorlock. The rough sketch of what I want to accomplish is as follows: A nice, clean aluminium plaque at the front door, providing bell buttons for my family, a separate button for my kids and one for the tenants. I chopped a old htpc case (Antec Mozart) for a nice 16x2 VFD display and the aluminium plaque with a display window. VFD is a necessity here, outdoor temperatures commonly drop to -25 degrees C (or colder), so no LCD would reliably work here. The VFD also has bright blue characters, perfect for those dark, gloomy winter nights.
I have purchased a few magnetic door contacts (http://www.clasohlson.no/Product/Produc ... d=55369098). A little experimenting with kaku magnetic door sensors left me disappointed. I do not want to surface mount ugly, expensive sensors and accept the lessened reliability of radio communication and battery changes, so i drilled a couple of holes in the doorframes in order to install these switches. They are practically invisible and work 100 % reliably. These will be wired to the arduino using a resistor ladder, thereby only requiring 1 pin and also giving me the possibility of monitoring a broken or cut wire.
In addition i have bought a pressure sensitive mat (http://www.clasohlson.no/Product/Produc ... =152538724), this will for now reside under the doormat at my familys entrance door, but later i will put it under my new wooden floor when i redo the hallway. This should provide the arduino with enough information to reliably estimate if someone is leaving or coming (door opens/pressure detected vs pressure detected/door opens), and display appropriate information on the VFD (house armed/disarmed, doors/widows open, turn on lights etc).
Today i ordered a simple RFID reader (TTL) and an antennae that should fit behind the plaque perfectly. Still on the buying list is a magnetic door lock for the front door.
My plan is to pull wiring from the front door and the sensors to a indoor arduino with a LCD display. i will run 12v to the front door and to the arduino situated next to our entrancedoor, and a network cable containing leads for the VFD, doorbells and sensors beetween the two doors. I should be able to see status of all doors, keep a small log of doorbell and door activity, and open the door with a switch. I have purchased a arduino network shield in order to forward all this information to my domotiga server (and possibly be able to open front door with sms or a web interface for kids, carpenters and my wife who forgets easily but is not easily forgotten)
Being a big project for me, I have started out with a simple doorbell. My arduino is now powered through the 12v ac using a home made circuit with a diode bridge, a couple of capacitators and a 5v voltage regulating IC. The exisiting doorbell wiring is hooked up to a optocoupler trough a diode bridge, capacitors and a resistor. When my doorbell is pushed, my arduino plays the Mario theme to the amusement of my kids (always entertain the masses if u need massive support). A SAE 800 tone generator was tried, but it's reassuring "ding-dang-dong" did not receive support, so we're sticking with mario.
Currently im hacking away in order to get the aluminium panel ready and all buttons installed. Using a small motion detector (https://www.elfa.se/elfa3~eu_en/elfa/init.do?toc=20135) to turn on/off the outdoor vfd (and log more data) is an option, but that will be put on hold for now. Hopefully I'll locate my camera one of these days and take some pictures and eventually provide you with schematics and code.