Best way to create an automatic lobby door opener?

I live on a third floor of an apartment building, and tired of using a key to open the lobby door. I was thinking of using Arduino and something similar to a car alarm remote to make the arduino open the door for 30seconds while I get to it.

What do you guys think is the best way to do this? is my idea even possible?

Thank you very much.

iceng6 years ago
Yes... can tenants buzz people in ?

If in the affirmative, an RFID tag in your pocket would be detected by a uP
which would authenticate and pull the latch on your lobby door, or
better an RF transmitter to your apartment Xbee receiver pushes your
ope button.
Eax5 (author)  iceng6 years ago
Yes you are right bout tenants are able to buzz people in.

I was thinking about RFID, but then I would need to placed the reading device in the lobby, since it will not be able to read from 3rd floor. Or am I wrong?

Can you please explain your second option in a bit more detail please.
iceng Eax56 years ago
You are correct about the RFID not reaching far enough.

Xbee is an RF transmitter and the 433 MHz RF transceiver is another of
many devices that can communicate up to a mile with a low cost
uP stamp or arduino sending a coded message to your apartment and
another identical uP that receives and decodes only your message.
Then a relay or semiconductor will be wired in parallel with the open
button in your apartment. 
Just like I can unlock my Subaru from 600' away.

Maybe eBay sells a low cost system for older cars you can hack.