This project uses proximity switches and relays to control a bank of indicator lights. The lights convey the occupancy status of two bathrooms.
Problem: Two single user bathrooms - in a dorm style house - are shared by multiple people, but the bathroom doors are not visible from the main hallway. This results in many failed trips down the hallway, only to find the one containing all of your toiletries or both (depending on what the need may be) are already occupied.
Solution: A centrally located visual indicator to convey the use status of the bathrooms.
Step 1: Inputs - Detecting Door Status
An assumption must be made to simplify the act of determining if the bathrooms are avaliable or unavailable. This determination will be based on the condition of the door. If a bathroom door is open, the bathroom is avaliable. If a bathroom door is closed, the bathroom is unavailable. The input I used for detecting the status of the door are inductive proximity switches.
Inductive proximity switches sense objects by generating a magnetic field. When a metal object reaches a certain distance from the sensors head, it will open or close a circuit (depending on the model). By placing a screw in the door, the sensor can be triggered when the door is closed.
Step 2: Relays - Control Box
This box is located in the attic. It receives the inputs from the proximity switches, and via relays, toggles the red/green light circuits and the - yet to be seen - door mounted fan.
The box contains two eight contact block relays and a 15 Amp breaker.
Step 3: Outputs - Lights and Fan
Once the relays are triggered from the closing of a door they break the green light hot lead, make the red light circuit, and - in the case of bathroom A - cut the power going to the door mounted exhaust fan.