Air Conditioner Controlled via PC or Internet - Attempt 4 - the Final Chapter

Rather than mess with the remote and possibly destroy it, I decided to cut my losses and just build a proper frame for the original solenoid idea in Attempt 1.

I bought a 1in x 2in x 6ft board from Home Depot. I cut, glued, and screwed it into as compact a frame as I could manage without blocking either the air conditioner's vent or control panel.

I wrapped the sensor leads in aluminum foil and mounted them using electrical tape.

This is a close up of the solenoid and driver. On the left is the back of the solenoid. On the right is an NPN transistor in a TO-220 package. I believe the transistor is a TIP120, which is much, much more powerful than I actually need for this project, but the board was salvaged from an old project. I used it as-is. Normally, I would just use a cheap MOSFET.

I added a small piece of foam board between the circuit board and wood. This let me mount the board with standard machine screws without requiring standoffs. The solder joints sit inside the foam board. Without the foam board, the solder joints would cause the board the sit unevenly and cause wobble and vibration. The foam board let me easily position the solenoid next to power button.

Below is a photo of the entire rig. I needed to tape a penny to the top strip of foil to get the switch to close when the air conditioner is turned off. The breadboard containing the microcontroller is not attached in this picture.

I'm glad I finally finished writing this project up by the end of August, just in time for it to be useful to no one (in the Northern Hemisphere, at least). Let me know of any questions or comments in the comments section!