I just completed a 8266 garage Door opener (https://www.instructables.com/id/IPhone-Android-8266-Arduino-Blynk-Garage-Door-Open/ ) After completing it I thought I really need a way to know if the door is actually opening and wouldn't it be handy to know if the door was still open. I thought of several ways in which I could do this with things like limit switches, distance sensors or even magnets. In the end what I decided to do was use a 10 turn Potentiometer (bar spins 7 times from open to close) mounted to the spring bar to measure the distance the door was open. Works great, and now I will always know how open/closed the door is.
You will need
1) an 8266 Board
2) a 10 turn Potentiometer
3) assorted wires
4) spur gear
Step 1: Add a Spur Gear to the Inside of the Spring Bar on the Garage Door.
In this step you just add a spur gear to the bar that has the spring for your garage door.
My garage door has a spring on the front of the door that is mounted on a bar with pullies on the end. All I did was take a spur gear I had from some hobby stuff I used to do and sanded it down to fit the hole in the bar. This was easy to do as I just put the gear on a drill bit and then took some sand paper to it while it was running on my drill press. Once I had it to the right size, I just glued it in to the hole in the bar and let it dry.
Step 2: Create a Mounting Bracket to Hold the Potentiometer
I took some aluminum bar that I had and just drilled an 8mm hole through it, then bent it so it would fit to another hole in the door rail. I took a bolt and nut and tightened that down.
Step 3: Put the Potentiometer in the Bracket and Screw It to the Spur Gear
Take the Potentiometer and remove the nut off the shaft. Put the Potentiometer in the bracket and then screw down the nut to hold it in place. Now, make sure the Potentiometer is turned to the completely closed position. Then spin it back about a 1/2 turn then insert the shaft in to spur gear and screw that down tight. Then finally mount that to the garage door rail to hold it in place.
Step 4: Solder the Contacts on the Potentiometer to a Piece of 3 Wire.
I used some Cat 5 I had lying around, I just stripped three wires, one for positive, negative and signal. Then I soldered the wires to the Potentiometer.
Step 5: Add the Wires to the 8266
Once you have the Potentiometer soldered to the wire, then move the other end of wire to the 8266. Hook the 3.3v to the positive wire, the ground to the ground and finally the signal wire to A0..
Step 6: Add a Gauge Control to Your Blynk and Hook to A0
Hooking this up for display is easy with Blynk, just add a new guage control to your form and hook it directly to A0. You are now done, your display should update and change when you open the door.