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FRONT DOOR REMOTE

Wireless keychain fob controls apartment intercom’s door buzzer. By Ryan O’Horo

Now don’t tell the co-op board, but I crafted a plan to ditch my Mul-T-Lock key for good. In my apartment building, you use the intercom to remotely unlock the front door for guests and deliveries. I upgraded my pocket keychain to get me into the building’s front door wirelessly and keylessly, using a fun $30 RF relay kit from Carl’s Electronics. Here’s how.

Photograph by Sam Murphy

First I opened the intercom panel in my apartment, exposing an unsettling mess of wires leading to its Door, Talk, and Listen buttons (Figure A, next page). The Door button is just a simple, normally open switch, so I used a continuity tester to find its 2 terminals. I stripped the ends of some 2-wire cable, screwed 1 strand to each terminal (Figure B), then closed the intercom panel with the cable running out for access (Figure C). Wiring in parallel like this allows either the relay or the button to open the door.

MATERIALS

2-channel RF relay kit part #HD2COMBO from Carl’s Electronics ( electronickits.com), $30

12V power supply

2-conductor hookup wire or phone cable Project enclosure, at least 2½"× 3½"× 1"

3M Command adhesive tape (optional)

TOOLS

Drill and small bit

Large screwdriver for intercom screws

Small screwdriver for kit terminal screws

Make: 147