Introduction: Acoustic Door Closer

Make your life easier with a door that closes with the right amount of sound. In our Engineering Design class we are currently working on a project where we have to design a smart product that uses sensors. Our group came up with the idea to use a sound impact sensor that can detect sounds to close a door. The idea is for the sensor to detect sounds and the door will close. The main application for this product is in a classroom setting, but it also has multiple other uses. The main purpose is for teachers to use when teaching a class with the door open. Teachers have to stop teaching when the hallway is suddenly filled with noisy students to walk across the room and shut the door. No longer will they have to stop class to close the door, the door will now close own its own when noisy students fill the hall.

Step 1: Materials

-1 9 Battery
-1 9v Hobby Motor
- Screws
-1 Plastic Wheel from Parallax item #721-00001
-1 HomeWork Board from Parallax item #555-28188
-1 Sound Impact Sensor from Parallax item #29132
-1 Solderless Breadboard from Parallax item #700-00078
-1 H-Bridge from Parallax item #603-00019
-2 Alligator Clips from Radioshack item #270-378
-Jumper wires from Parallax item #800-00016
-Spool of Wire from Home Depot (For wiring the sensor through the door frame and the wiring too long for the jumper wires.)
-Basic Stamp Editor v2.5.3
-2 L Brackets from any hardware store.
We also used various sizes of wood, but that is for our model door.
The motor listed above meant for our scaled down model door and will not likely work on the bigger or heavier doors, but may work on normal doors that are light weight. For the bigger and heavier doors you might want to use a motor with more power and maybe a bigger wheel.

Step 2: Designing a Model Door

First, we designed and created a scaled down model door. The model needed to be scaled down because we are only using a little hobby motor for power. The door has slanted sides so it can stand up on its own.

Step 3: Drill a Hole

Drill a hole through the door frame. The hole is for passing wires through to connect the Sound Impact Sensor with the HomeWork Board and Breadboard. You can use a smaller hole size if you want, we just used this size because it's what we had to work with.

Step 4: Soldering

You need to solder the the prongs of the Sound Sensor to three different wires. These are the wires that will pass through the hole in the frame. Without soldering the sensor would need to be attached to the homework board.

Step 5: Wiring

This is how we wired our sensor to the homework board and the breadboard. The diagram shows the same thing, but more organized and easier to read. This is where we used the H-bridge that allowed use to control the motor.

Step 6: Coding

' {$STAMP BS2}
' {$PBASIC 2.5}
PAUSE 1000

FOR move = 1 TO 10
PWM 2,0,100

This is the code for the sound sensor to detect any sounds loud enough to set it off. When the sound sensor is set off it will activate the motor and cause the door to close. Depending on the size of the door you will need to adjust the code to run the motor longer or shorter so it can fully close the door. To adjust the range the sound sensor will detect sound at just turn the knob on the sensor accordingly.

Step 7: Frame

Now we need to build the frame that the wheel will run on to close the door. You need to attach a piece of wood that is about the length of the door to the door frame. You then need a flexible piece of wood that will bend from the attached piece of wood to the other side of the door frame. You will also need to attach the wheel and motor to the top of the door with L brackets so it can run along the frame. There needs to be as little resistance as possible between the wheel and the frame because if their is a lot of resistance the motor won't turn. You will also need to hit the reset button on the homework board after the door closes because it is programmed only to close once so that the motor isn't spinning for every loud noise it detects.