Personal Keyless Entry System.

Here is an effective yet simple keyless process for converting a regular apartment intercom into a personal keyless entry system. This will be a great as many shared apartment buildings have a common door for letting the residents to allow visitors inside.
"My apartment building, of course, uses an intercom system to remotely unlock the front door for guests, deliveries, etc. This keychain upgrade gets me in the front door... keylessly.
This panel has a "Door", "Talk" and "Listen" button. The "Door" button is normally-open and the circuit is about 22V. In the following steps we're going to effectively bypass the button with our own circuit."

<a href="http://www.youtube.com/watch?v=O9VTfzYiOQg">Watch Personal Keyless Entry System Video on Youtube</a>

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