That Special Visitor (or how to securely let someone into your house on the cheap)

08/27/2009 14:32

Because I keyed every lock in my house off a master, I don’t like letting anyone borrow a key.  If I were to lose a key, it would require changing 11 locks.  It takes me on average of 20 minutes to rekey a lock (yes, I’m very slow) so I came up with a way to let people into my house without giving them a key.  I happen to have a magnetic card reader on my house but this system works with just a common electric door strike that will cost $30.  The second item you’ll need is an X-10 Powerflash interface (runs about $20).  Wire any conventional door bell into the powerflash.  I used an old intercom transmitter unit that I found.  The receivers are the expensive part and you can usually find transmitters all over the place.  I think I got mine off of the wall at a car dealership.  It had been sitting there unplugged for 15 years.  Wire the doorbell into the powerflash.  It will send an X-10 code that the doorbell has been depressed.  Then you can use an X-10 chime to ring the bell.  This allows you to place the bell anywhere in the house you would like. 

But the fun doesn’t stop there.  Because you can use another powerflash to trigger the door strike.  This allows your home automation system to open the door.  No more locking yourself out.  If you can get to a phone, you can get into your house (password protected, of course).  But I got to thinking.  What if I would like to let someone in to my house without having to manually trigger the strike.  Pretend for a moment that I was wealthy enough to afford a housekeeper.  If she planned to come every Tuesday morning between 8 and 9, I could easily program the doorbell to trigger the door strike if depressed twice within 2 seconds between the hours of 8 and 9.  The housekeeper doesn’t have to keep track of a key and I don’t have to worry about my house being at risk for the other 167 hours in the week.  As an added firewall, I configured the alarm system to only disarm with the visitor passcode between those same hours.