User:1sfoerster/Access Control

Problem Statement
Access through doors into shared space is a problem in any institution. People who use the doors have different objectives than security, disaster planning, administration and space owners. Most doors need unique, custom designed security solutions that don't involve passing out physical keys. The goal is to build a simple, temporary solution that can be mounted on any door.

Motors to turn door knob
Stepper motors salvaged from fax, scanners and inkjet printers are not strong enough to pull a door handle. Gearing up or building a new mounting assembly is very difficult.

A AC paper path motor out of a laser printer was found still mounted to all it's gears. An arduino with a powertail can be used to switch the AC motor off and on. Originally there was a mechanism in the gear box to switch direction using a relay so that the motor can be release the door knob also. If positioned correctly, it may be powerful enough to open the door.

Microphone to pick up knock vibrations
An additional throat mic was ordered to improve "listening" over the piezoelectric speakers turned into microphones.

Arduino Program
Pre-made Arduino program that takes the input from knock and output to motor found here.

Input Sensor
Tried attaching mic to Arduino Analog input 0 through cell phone jack and wires. This was unsuccessful. Knock program says it needs 1 megohm resistor. Knock program responds to knock sound and will light up LED.

Audio Jack to Arduino
To connect the audio jack to the Arduino we first needed to test which part of the audio jack was related to the ground, and which to the signal. To test this first we took the end of the mic with the audio input and did a continuity test with a multimeter on the tube, and we found the corresponding port on the other end. We then did the same with the tip of the audio input.

Next Steps for Throat Mic

 * Add amp between throat mic and audio jack.

Piezo Sensor as Input
The program waveform was used as an oscilloscope. The output from the piezo sensor was between 30mV to 40mV. This needs to be approximately 4-5 volts. Attempted building an op-amp on breadboard to fix. Did not work. Not sure why.

Next Steps for Piezo
Follow documentation on how to build audio input for arduino found here. Isolate problems.

Door Mount
Goal was to attach board to door. Additional work found here.

Harness to Board
There were previously drilled holes in the board for the harness, but they needed to be bigger. The harness hook measured .351 in, but ultimately the hole was created with a .422 in drill bit.

Board to Door
Tested the board and harness on door. There was a large gap. This is a problem, because the mount needs to be very stable. Needs stabilized.

Stabilizing Mount
To stabilize mount, bumper was needed. Used skateboard wheels, they were good thickness and provided friction on door because of their texture. This was tested and works perfectly.