HOW-TO: Set up keyless entry to your house via your cellphone
This week's how-to is brought to us by special contributor Chris Turek, who would like to thank Rob Augusta for
his help and electrical expertise.
My inspiration for this project: I walked up to my building and started pulling out my keys when the guy next to me
pointed his cell phone at the front door and it buzzed us in. I was in shock. When I asked him how he did it he laughed
and said he was actually just hanging up the phone with his girlfriend and she buzzed the door. I immediately realized
what I had to do. I had to figure out a way for my cell phone to buzz open my front door.
My objective: To trigger the door buzzer in my apartment from a phone or more precisely, my cellphone. I began scouring the Internet. My first thought was an X10 device but nothing seemed right. With all the X-10 devices the phone had to pick up, you had to put in a security code and then a code to operate the device. Also, most X10 devices worked on existing phone lines so they did not answer the phone for 30 seconds. This made X10 impractical. I came across the ELK 930 and I knew I found what I needed. The ELK 930 detects the rise in voltage on a telephone line when a phone is called. Since the 930 is not a relay I needed a relay so I could trigger my door buzzer. So Elk came through for me again with the ELK 960, which is a timed relay.
Check out the PDF diagram for the overview of how it all
works.
Here is a list of everything that is needed:
1) For the phone line I used a VOIP phone line by using a Linksys - Sipura SPA-1001 and an account with Teliax. This
is about $50 up front and $6 a month service fee.
2) To detect the ringing of the telephone I used an ELK 930 purchased at
www.bassburglaralarms.com for $30.
3) To activate my door buzzer I used an ELK 960. Purchased at
www.bassburglaralarms.com for $18.
4) 1N4004 Diode. If you know what this does stop reading and do it yourself because I still have no idea. Purchased at
Radio Shack for $.50.
5) A 12 volt DC power supply I used an older blackberry charger and cut the end off. Any 12-24 volt DC power supply
will work.
6) A volt meter (not required but good to have).
7) Standard 2 wire phone cord. Purchased at Radio shack for $5.
Procedure:
Step 1) Cut one end off the phone cord and strip the two wires. Now connect the 2 wires to the T and R on the 930. I am 98% sure it doesnt matter which one goes where. I have the red on the R (ring) and the green on the T (tip).
Step 2) Run a wire from the negative on the 930 to the negative on the power supply. I spliced this wire onto the wire
that was already attached to the power supply. If you do use an existing power supply and cut the end off like I did,
make sure to use a volt meter to figure out which side is positive and which is negative.
Step 3) This step is probably the trickiest. You need to run a line from the negative on the 960 to the negative on the power supply but you need to put the diode inline. The diode has to be hooked up in the correct direction. The silver band on the diode should be on the side of the diode closest to the power supply. I hooked up one end of the diode to the two wires I spliced together in step 2 and connected the other end of the diode directly into the 960 (see picture). This probably isnt the best way but it worked for me.
Step 4) Hook the power supply positive output to the 960 positive terminal.
Step 5) Connect the out terminal of the 930 to the Trigger (TGR) terminal of the 960.
Step 6) Make sure all the jumpers on the 960 are set correctly. JP4 must be set to A and JP5 must be set to - (negative). JP2 must be set to 1 shot or the relay will continually trigger itself (I learned this one the hard way). JP3 should be set to begin. JP1 should be on SEC which means the dial ranges from 1 - 60 seconds. My dial seemed to be very sensitive. A very small movement could be 5 seconds.
Step 7) Go over your connection one last time then plug in the power supply. The relay should trip as soon as you plug it in and stayed tripped for whatever the timer is set to. If you unplug the power supply leave it unplugged for at least 5 seconds or the 960 doesnt trip the relay when plugged back in. Im not sure if this matters though.
Step 8) Plug the other end of the phone cord you cut in step 1 into your phone jack. At this point you should have
everything connected and working except the connection to the door buzzer. I suggest testing now before hooking it up
to your door. If the relay is triggered you did everything right so far. If not, this is where you need the volt
meter.
If everything worked all you need to do is hook it up to your door opener. Mine was very simple. I opened it and it
was obvious that all that happens when I pushed the door buzzer button was it closed a circuit. If you dont know what
that means you probably didnt get this far. If you are not sure how to hook this up to your door buzzer I recommend
you ask someone with some electrical background. I have a very limited electrical background and I figured it out
without much trouble. If you have a newer model this might not be the case. I have no idea if the newer ones work the
same but I would guess they do. If you have a problem hooking up the ELK devices I suggest calling ELK their tech
people were great. Good luck. I would also suggest holding onto the 2 plastic containers the ELK 930 and 960 came in. I
used one of them to hold this setup so it was nice and neat and my girlfriend wouldnt complain about wires
everywhere.
Reader Comments (Page 1 of 2)
gorillak @ Dec 19th 2005 1:26AM
Cool post fellas. Gonna try this one out for sure.
Daryl @ Dec 19th 2005 1:26AM
But I dont have a door buzzer in my apartment, Im sure only 1% of the people that read engadget have a door buzzer. Damn I was really excited for a min.
Jacky @ Dec 19th 2005 1:26AM
an inventor in hong kong already got a patent for this. he even furthered his idea to the automobile, where you can unlock, startup-, windows up/down, music, lights, and stuff.
Gram @ Dec 19th 2005 1:26AM
So all someone needs to get into your apartment is the right phone number?
Not sure this is such a good way to do it.
GeneMack @ Dec 19th 2005 1:26AM
Great article.
I have a door buzzer for my condo, but I can go more simple, since I am the front unit and a simple RF keyfob and contact should do the trick.
But I wouldn't have thought of it until I read this. Thanks!
Infinite93 @ Dec 19th 2005 1:26AM
Cool Hardware hack, but... It looks like anyone with your phone number can now buzz into your apartment. Could be handy, could be VERY dangerous (or just annoying)
josh @ Dec 19th 2005 1:26AM
Great Walkthrough I almost wish I had a door buzzer to put this to use.
Would have been fun to try and hack it into the security switches on campus last year.
I would really love to figure out a way to use the 2nd vehicle switch on my car alarm to unlock my apt door.
I think it would be only of medium difficulty more mechanical than anything. If I could actually hack my door apart I would try it. O well the cons of renting.
Morwan @ Dec 19th 2005 1:26AM
It seems like it would be smarter to use some sort of Bluetooth or IrDa method. If any phone call to that line opens your door, well, I'd imagine that telemarketers could randomly open your door.
But it's a pretty cool idea.
Charles @ Dec 19th 2005 1:26AM
This is really cool. ive been wanting to do this for a while, but i was thinking of using an IP connection/serial port and a basic stamp to do it.
Dustin3000 @ Dec 19th 2005 1:26AM
Uh, I don't think the posters above understand...
Most appt buildings have buzzers to get into the building, not your apartment. Most actually have two separate doors to get inside. You have to get one set of keys for the outer doors, then once inside, you have your own appt key. This is highly annoying, especially if you're carrying something.
And, I'm sure more than 1% of people that read this live in buildings such as this. Pretty much every building in all large cities (NY, SF, Chicago, etc) is set up like this.
John Laur @ Dec 19th 2005 1:26AM
What if someone calls you while a transient is hanging out outside your building? The door just opens up?
It would be wiser to at least base this on matching Caller ID. Although CID can be easily spoofed it's going to probably be secure enough for building access where plenty of other things are less secure (tailgating, everyone else who lives in your building, etc.) There are uC's and plenty of samples out there for reading CID info and you could easily have them click a relay for you.
skuzmak @ Dec 19th 2005 1:26AM
most apartments/condos have buzzers tied into the phone system. At my old condo I didn't have a landline, I used my cell (they just asked for a phone number). I could then buzz my condo, which would ring to my cell, then i would just answer and hold down 9 to open the door. worked great, quite secure.
Andir @ Dec 19th 2005 1:26AM
The fact of the matter is, if you receive alot of phone calls, they apartment complex will most likely track down why the door keeps buzzing...then again, I had a neighbor try to break out the window to get in because he left his keys in the house and there was nobody to "buzz" him in because the apartment office was closed.
Alex @ Dec 19th 2005 1:26AM
Dude, great work setting it all up, and the fact that it was a scratch design is awesome.
On a simmilar note Silicon Chip magazine here is Australia had an article on how to control your home using SMS
http://www.siliconchip.com.au/cms/A_102670/article.html
It works by pulling SMS codes from a dedicated Nokia phone on a prepaid plan, and activating outputs. You can therefore have multiple SMS codes (in plain english) control different tasks, such as sprinklers, aircons, doors etc.
The controller also works in the opposite direction, by SMSing you when an alarm is triggered.
The kit is available in various places such as http://www.dse.com.au for about A$65 (US$40ish)
telemarketer @ Dec 19th 2005 1:26AM
Cool, just make sure to put your door on the Do Not Call list.
Andre @ Dec 19th 2005 1:26AM
My apartment complex has a dial pad that calls your home phone and once you answer you have to press a key (9 or 5 etc) to open the door. There must be some intelligence so that only the door you are calling from is opened on key press.
Is it possible to build a system like yours to solve this problem? I was thinking of connecting the phone line to a PC and wait for a PIN... any suggestions ?? :)
hong @ Dec 19th 2005 1:26AM
if you read TFA you'd see at the end he mentions his gf
Chad in Austin @ Dec 19th 2005 1:26AM
Pretty cute. Reminds me of the time I shared an apartment, but didn't have my own gate entry remote. At the gate was a call box which simply dialed our home phone number so we could speak with them through an intercom and buzz them in by pressing "9". So I recorded the "9" sound onto the beginning of our answering machine message. Anyone buzzing our apartment from the gate could get in when it answered, but it was usually just me.
no3rdw @ Dec 19th 2005 1:26AM
Awesome. If the building I'm living in had (working) door buzzer / unlocker, I would do this in a second.
People posting comments are forgetting that A) this is only the outside door, not the door into his actual apartment and B) he bought a seperate phone line, so it's not like his door is swinging open every time he makes a call from his cell phone.
jordan @ Dec 19th 2005 1:26AM
i've been searching for a hack to open my garage door via cell phone for some time now
Dino Gelato @ Dec 19th 2005 1:26AM
Cool but why don't you just have your apartment manager have the buzzer ring your cell phone so when you need to buzz yourself in you just punch in your code. It rings your celly then you buzz yourself in.
Chris Gregg @ Dec 19th 2005 1:26AM
Cool idea, great implementation. Another way to do this, if you have a networked PC in your house, would be to send an SMS to AIM and have a script buzz the door (setting the control up through the parallel port would be pretty easy). I'm going to look into this...
-Chris
steve @ Dec 19th 2005 1:26AM
cool hack - but i use a method that is free and requires no power or phone line... a key.
Like the thinking though. look forward to more cool hacks like this one - Thanks engadget.
Andrew @ Dec 19th 2005 1:26AM
Another variation for apartment dwellers where the entry system dials your phone number so you can punch a key to open the door: Instead of having the system programmed to dial your mobile, use a Vonage or other VOIP line with which can be programmed to simultaneously ring a forwarding number. Program it to simultaneously ring your mobile. This setup allows you to use either your VOIP line OR your mobile to answer and open the door.
Rob @ Dec 19th 2005 1:26AM
Slightly OT: How does one go about creating these little gadgets? I have never found anyone who could tell me where to go to learn how to build simple solutions with electronics. Any suggestions?
Patrick @ Dec 19th 2005 1:26AM
What about RFID locks? Doesn't it do the same thing essentially? Supposedly, a lot of people in Korea use RFID locks, and put small RFID chips on their cell phone/watch/keychain to get the same effect as this do-it-yourself. Engadget did a story on one of them -
http://www.engadget.com/entry/1234000153044323/
The website for this lock (http://www.MyKey2300.com) talks about using your cellphone to unlock a door. Any experiences?
Roscoe @ Dec 19th 2005 1:26AM
How about implementing this idea for a CAR . i.e. unlocking your car with the cell phone ? ..
David @ Dec 19th 2005 1:26AM
I don't have a phoneline! Just Skype via cable.
Erm... maybe I should be looking at garage openers.
Something I can fix to my bicycle somewhere and buzz the door open without having to search for keys when it's raining.
UKMuFFiN @ Dec 19th 2005 1:26AM
can't you afford a real key?
UKMuFFiN @ Dec 19th 2005 1:26AM
can't you afford a real key?
David @ Dec 19th 2005 1:26AM
Can't help thinking i could find a use for my old mobile phone in this set up instead of wiring in the phoneline. Just wire the speaker to the door relay. Must find out about replacing the locks on my door as well. I wonder, though, if there is a circuit that wil just detect the presence of my mobile and open the door. Hands free.
ch424 @ Dec 19th 2005 1:26AM
Nice hack! Quite expensive though... the dedicated Nokia idea that Alex (#14) posted sounds a bit more elegant.
The diode is so that the ELK board doesn't get fried when the electric lock switches off and sends a massive current back along the wire. It's called back-emf.
ch424
Mark @ Dec 19th 2005 1:26AM
I think that this is an absolute waste of time.
This guy just spent more time and brain power than it will EVER take (cumulative) to open a door using the key.
Unitl they have an integrated (and secure) solution for an entire house, i'm going to steer clear of this type of thing.
LC_ @ Dec 19th 2005 1:26AM
"I immediately realized what I had to do." Go get a girlfriend?
ShARamM @ Dec 19th 2005 1:26AM
Poster number 16 (LC_ ), you are a moron. Go figure out how to hook up a cell phone to a swedish penis pump and your junk could grow to about 1 inch IF you actually had the smarts to get it to work.
noel @ May 30th 2007 7:19PM
You wouldnt happen to kno the name of that inventor was would you?
ScaredyCat @ Dec 19th 2005 1:26AM
I've been doing something similar for a couple of years now, only with the garage door (attached to the house).
I use a combination of a relay with asterisk.
Using asterisk allows me to protect opening of the door via a series of passwords entered on the phone (DTMF). This means that only those with the passwords can actually open the door. It also means I don;t need to sign up for another service since I can call in on my standard PSTN line.
It's also worth pointing out that there are lots of services that will give you a FREE pstn number and route it to your sip proxy/asterisk box - that $56 could be better spent on more gadgets!
scott @ Dec 19th 2005 1:26AM
Two things people obviously missed..
it's a separate phone line. the door won't buzz every time he gets a call.
that people could open the building's front door (note, not his apartment door) by calling that number is true, but no one but him knows the number. This to me is the equivalent of a seven digit code on a keypad. No one's going to guess it.
Lastly, yes, it would be easiest to just open the door with a metal key. But we wouldn't bother to read about that, now would we?
Ron @ Dec 19th 2005 1:26AM
So, the relay triggers the first time you plug it in? I.e., it also triggers when power comes back up, say after an outage? Are your circuit breakers accessible from the outside? :)
Daniel Jefferies @ Dec 19th 2005 1:26AM
I use RFID locks in my building. It is the same thing as a key except with nothing to insert. You wave the RFID "key" passed the reader and your in. I've also used corporate ID badges with RFID built in. In both cases the reader didn't have enough range to produce the cool, "door opens automatically as I approach", effect that I was hoping for.
tatlow @ Dec 19th 2005 1:26AM
Based on some of the security considerations. It seems like controlling a relay from your computer would be the easiest thing to do.
Have a script poll an email account or use centericq to sit on AIM or something. Most phones can sent email or IM. Once the trigger occurrs then have it flip the relay.
If you really wanted to be fancy have it poll flickr for a photo from your camera of you standing in front of your door...
Cary Menage @ Dec 19th 2005 1:26AM
I am currently using Asterisk integrated with our Accees Control software at work to provide Caller ID and PIN # authentication to give the end user a customised voice menu with different options for different doors. Each user can have different doors based on their need or authority, and if any joe shmoe accidentilly calls, he will just get a recording of my choice.
The thing about someone patent this is rediculious, I have been in this industry (electronic security) for nearing 20 years and this is nothing new (telephone entry, DTMF to Relay)
I would caution anyone to consider that if your door is only secured by an electronic strike, it had better be a good one, in order for this to work, you can not have additional deadbolts etc.., thereby weakening your physical security to that of the quality of your strike, maglock and installation of such.
Great Devourer @ Dec 19th 2005 1:26AM
A simpler way of doing this than with the ELK board, would be to get a cheap PayAsYouGo cellphone, and gut it, so that the circuit going to the speakers is diverted to a transistor, with the buzzer on base, phone on collector and door on emitter. In fact, I may do that...
oshean @ Dec 19th 2005 1:26AM
For those of you who live in the suburbs.... wire your garage door opener to your vehicle's high beam circuit. A simple flick of the high beams and open sesame.
siggy @ Dec 19th 2005 1:26AM
This is not a big deal. I live in an apartment that use RFID cards to get into the building. When I forget my wallet all I do is have the call box dial my cell phone and I pick up and press "6". It unlocks it for me from my cell phone.
I think more newer apartments have it where your home phone is the "buzzer". The box routes calls and looks for the DTMF key that's needed to unlock.
Alan @ Dec 19th 2005 1:26AM
Neat idea. Have you thought of connecting it to a microcontroller to accept a touch tone code? That would be kinda slick, one code to open the door, another to turn on the lights...
ScaredyCat @ Dec 19th 2005 1:26AM
Just found this while looking for something else... much easier :D
http://www.flexipanel.com/BTAccess/index.htm
Wintermute @ Dec 19th 2005 1:26AM
That bluetooh device is cool, however if you live in a 20 story apt building you might be out of range at the front door of the apt.
james @ Dec 19th 2005 1:26AM
house?
sorry i dont have a buzzer on my house...
apparently neither does the guy that made this BECAUSE HE LIVES IN AN APARTMENT!
would it be too much to ask to figure out the difference between a HOUSE and an APARTMENT engadget?
John @ Dec 19th 2005 1:26AM
They actually have phone interactive X10 devices out there. These device respond to preset codes that you input while on the phone with the device, rather than just being activated by the incomming ring.