Juan Ferrer and Jorge Cases built a liquid tester, with only two wires and a resistor, which can measure the resistance of a liquid. Because every liquid has a different resistance you can separate different drinks like water or orange juice. With some Processing code you can do something nice with those values.

How to make your own liquid tester:
You need an Arduino, some wires and a 10K resistor.
Upload the standardFirmata to the Arduino, read this for more info.

// Detector de Liquidos (Liquid Detector)
// By Juan Ferrer and Jorge Cases
// open this file in Processing and upload the Standard Firmata to your Arduino
// connect the wires to the analog input port number 0

import processing.serial.*;
import cc.arduino.*;

Arduino arduino;

color off = color(4, 79, 111);
color on = color(84, 145, 158);

color blueColor = color(0,0,250);
color orangeColor = color(255,128,0);

int heightVal = 280;
int widthVal = 470;
int adjust = 20;
PFont fontA;

void drawGraph() {
  line(adjust,adjust,adjust,heightVal-(adjust*2));
  line(adjust,heightVal-(adjust*2),widthVal-(adjust*2),heightVal-(adjust*2));
}

void setup() {
  size(widthVal, heightVal);
  arduino = new Arduino(this, Arduino.list()[0], 115200);
  fontA = loadFont("CourierNew36.vlw");
  textFont(fontA, 32);
}

void draw() {
  background(off);
  stroke(on);

  drawGraph();
  int value = arduino.analogRead(0);

  if (value < 980 && value > 900) {
    fill(blueColor);
    text("this is water", 200, 90);
  } else if (value<800 && value > 700) {
    fill(orangeColor);
    text("this is orange juice", 200, 90);
  }
  else {
    fill(off);
    text("", 200, 90);
  }
  println(value);
  rect(adjust,heightVal-(adjust*2),50,-(heightVal-(adjust*2))*value/1024);
  delay(500);
}

download processing.org code

Use this script if you always wanted to now at which time your colleagues enter and leave the office.

What does it do?

It will scan the local network every minute for predefined computernames. If this returns a true than the computer is switched on and the colleague is probably at the office and it will send ‘John Doe has entered the office’ to a Twitter page.

How can I use it

Currently the script is only tested on Mac OS, it shouldn’t be so hard to convert it to a script that is working under Windows, ‘nmblookup’ should be replaced with ‘ping’. Please leave a comment at this page if you have this script working in Windows.

Source files:

» Download Processing code + PHP source files