In short, this project allows activation of buttons on a physical remote control of some sort (here it's a garage opener but could be a TV or stereo remote, for example). The board uses transistors as switches, and in this particular design I found that the remote and board need to share a common ground (not a problem here as the remote takes power from the controller instead of a coin cell).
See previous project for more description about how the system functions.
The improvements over the previous project are:
* relays have been switched out for transistors,
* remote is now powered from the 3.3v pin of the controller,
* a piezo speaker plays a tune on activation of a gate (diff