I am using an UNO and I am trying to get it to open and close my garage door using the old opener. I removed the push button from the garage door opener circuit board, but I am not able to short the to points on the circuit board to activate the garage door. How do you get and UNO to short two pins on a circuit board?
You need a relay. It acts like a switch that will be controlled by the Arduino.
Here is an example, I do not know the seller... http://www.ebay.com/itm/1pcs-5V-1-Channel-Relay-Module-with-Optocoupler-H-L-Level-Triger-for-Arduino-/121258081911
Thank you. I realized later that is what I would have to do and what you suggested is a good price.
Here's what I did. First break the connection between the battery and the PCB in the remote and bring 'both sides' of this out (the battery connection and the place it used to be hooked to). In my case I cut the clad on the board for the negative battery contact.
I then connected a general purpose NPN (2N3904) transistor to the Arduino output I wanted through a 1K resistor to the base with the emitter grounded. The collector goes to the more positive of the two wires from the remote (PCB in my case, but the battery if you cut the positive side). The other connection from the control (in my case battery minus) goes to ground on the Arduino. When the output goes high the transistor turns on basically reconnecting the battery in the remote.
All you need to do is tape down the button (or in your case since the switch is gone, short the switch contacts).
The remote 'comes to life' transmitting.
It's working well for me. Good luck with it.
108buz told us he wants to open as well as close the door. That would require 2 remotes, when opting for RetiredGuy's approach.
I've also seen some attempts of people that were using a (or multiple) servo to actually push the buttons on a remote. Don't know how that ended up.