I saw this project about opening the door with a secret door knock
Re: Door opener
Posted: Fri Jan 31, 2014 6:52 am
by thechad
I have done this also but using a capacitive touch sensor and an arduino. You need to touch in a defined pattern with a small tolerance between the timing and length of the taps.
I had it opening the garage from outside if i forget my keys. Ran a small rod through the brickwork to the outside for touch sensor...was almost invisible. Worked well.