Category: Uncategorized

NFC Glass capsule 12mm x 2mm 13.56Mhz

Posted on by John McLear

I managed to source some 13.56Mhz 12mm x 2mm NFC Glass capsules / tags from China and I’m happy to sell them for 10$ a piece. If you want one please contact me, I’m too lazy to list them on any online auction stores etc.

The read range is pretty much limited to contact when using them with a mobile phone reader or other low range reader device.

They are not sterilized so should not be used for human implants and they are based on the NXP semiconductors 15693 chip.

They are read/writable, not Mifare (See above).

The MoQ for is 500 and at that point the price drops to 5$ per unit.

Special offer during Feb/March 2013 — Order 20 tags for just 160$

CSS rainbow

Posted on by John McLear

Chrome only, very easy to port to firefox/IE

.rainbow {
  /* Pretty rainbow colors chrome */
  background: -webkit-gradient(
  linear, left top, left bottom,
  /* red */
  color-stop(0%,rgba(255,50,50,1)),
  color-stop(13%,rgba(255,50,50,1)),
  /* yellow */
  color-stop(14%,rgba(238,255,50,1)),
  color-stop(27%,rgba(255,224,50,1)),
  /* pink */
  color-stop(28%,rgba(255,50,248,1)),
  color-stop(41%,rgba(238,50,255,1)),
  /* green */
  color-stop(42%,rgba(42,201,40,1)),
  color-stop(55%,rgba(0,160,11,1)),
  /* purple */
  color-stop(56%,rgba(122,24,122,1)),
  color-stop(69%,rgba(122,24,122,1)),
  /* orange */
  color-stop(70%,rgba(255,146,50,1)),
  color-stop(83%,rgba(255,139,50,1)),
  /* blue */
  color-stop(84%,rgba(30,87,153,1)),
  color-stop(100%,rgba(30,87,153,1))
  );
}

Apply the rainbow class to your element IE 

<div class=rainbow>...

Gas sensor with an alarm

Posted on by John McLear

My first arduino project thanks to Tom Hudson for lending me his Uno

Very simple code, comments should explain it:

I’m using an MQ2 gas sensor.

#include "pitches.h"

int gasSensor = 0; // select input pin for gas Sensor
int val = 0; // variable to store the value coming from the sensor
int greenLed = 3; // the LED port
int redLed = 4; // the LED port
int speaker = 8; // Speaker

// notes in the melody:
int melody[] = {
  NOTE_C4, NOTE_G3,NOTE_G3, NOTE_A3, NOTE_G3,0, NOTE_B3, NOTE_C4
};

// note durations: 4 = quarter note, 8 = eighth note, etc.:
int noteDurations[] = {
  4, 8, 8, 4,4,4,4,4 
};

void setup() {
  Serial.begin(9600);
}

void loop() {
  val = analogRead(gasSensor); // read the value from the pot
  Serial.println( val );
  delay(100);
  if(val > 100){
    digitalWrite(greenLed, LOW); // turn the green LED off by making the voltage LOW
    digitalWrite(redLed, HIGH); // turn the red LED off
    
    // iterate over the notes of the melody:
    for (int thisNote = 0; thisNote < 8; thisNote++) {

      // to calculate the note duration, take one second 
      // divided by the note type.
      //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
      int noteDuration = 1000/noteDurations[thisNote];
      tone(speaker, melody[thisNote],noteDuration);
  
      // to distinguish the notes, set a minimum time between them.
      // the note's duration + 30% seems to work well:
      int pauseBetweenNotes = noteDuration * 1.30;
      delay(pauseBetweenNotes);
      // stop the tone playing:
      noTone(speaker);
    }
  }else{ // everyting okay.
    digitalWrite(greenLed, HIGH);  // The the green LED on
    digitalWrite(redLed, LOW);   // The the red LED off
  }
}