my "sun jar"

Tried to make my own "sun jar" around a year ago. Left it on breadboard until today...

Find the schematic below. Added a switch to keep the LED off all the time... which effectively makes the whole thing a solar powered battery charger...

Notes to self:

1. The solar panel is directly connected to the battery for charging. Without any control on voltage or current. May damage the battery in a long run. But then, the solar panel used is not that powerful... so....
2. A normal LED requires more than 1 AA cell to power it up. To overcome this, the center-tapped-coil and one of the transistor formed a switching circuit. It generates voltage high enough to light up the LED with less than one volt.
3. Unlike the commercially available Sun Jar, this circuit doesn't use photoresistor to control when to light up the LED. Instead, a transistor is used to detect the voltage output of the solar panel.

Arduino test: voltmeter

First experiment with Arduino. Trying to implement a voltmeter.

Each analog input of Arduino has 1024 steps. From 0 to 5 volt. This experiment used a simple voltage divider to measure roughly 0 to 12 volt (using 50k as R1 and 4k3 as R2).

By varying the values of R1 and R2, the precision and range of the measurement can be changed.

Here is the Arduino code:

// variables for input pin and control LED
  int analogInput = 1;
  int LEDpin = 13;
  int prev = LOW;
  int refresh = 1000;
  float vout = 0.0;
  float vin = 0.0;
  float R1 = 50000.0;    // !! resistance of R1 !!
  float R2 = 4300.0;     // !! resistance of R2 !!

// variable to store the value
  int value = 0;


void setup(){

  // declaration of pin modes
  pinMode(analogInput, INPUT);
  pinMode(LEDpin, OUTPUT);

  // begin sending over serial port
  Serial.begin(9600);
}

void loop(){
  // read the value on analog input
  value = analogRead(analogInput);
  //Serial.print("value=");
  //Serial.println(value);

  if (value >= 1023) {
    Serial.println("MAX!!");
    delay(refresh);
    return;
  }
  else if (value <= 0) {
    Serial.println("MIN!!");
    delay(refresh);
    return;
  }

  // blink the LED
  if (prev == LOW) {
    prev = HIGH;
  } else {
    prev = LOW;
  }
  digitalWrite(LEDpin, prev);

  // print result over the serial port
  vout = (value * 5.0) / 1024.0;
  vin = vout / (R2/(R1+R2));

  //Serial.print("vout=");
  //Serial.println(vout);

  Serial.print(vin);
  Serial.println(" volt");

  // sleep...
  delay(refresh);
}

Arduino & LCD Smartie

Here is a test of Arduino with LCD Smartie. You can get the Arduino sketch here.

開箱文…

早兩日係淘寶 order 的新玩具…

Arduino 主板 + LCD and input shields

先試主板…

合體!

試 LCD panel

是日金句

「人多自然容易受傷」

人神共憤

Windows Server 2008

Trying out Windows Server 2008. Tested it in VMWare 5.x (!) on Windows 2000 (OK, so I am still using Windows 2000 on my main machine). Hardware is AMD 4200+ with 2G RAM. And here are some tips on "converting" a Windows Server 2008 to a workstation.

BTW, if you are/were a high school or university student,go to DreamSpark to download Windows Server and Visual Studio etc for free.

是日金句

「不要嘗試尋找刻意失蹤的人…」


…因為佢無意俾你搵到佢…

未來 & 後來

Converting MKV files for PSP

Here is the command I used to convert MKV files for PSP:

mencoder 5centimeter.mkv -font c:winntfontsmingliu.ttc -subfont-text-scale 3 -vf pullup,softskip,dsize=480:272,scale=0:0,harddup,unsharp=l3x3:0.5 -sid 1 -slang chi -ofps 24000/1001 -oac faac -faacopts br=128:mpeg=4:object=2:raw -channels 2 -srate 48000 -ovc x264 -x264encopts bitrate=500:global_header:partitions=all:trellis=1:level_idc=30:threads=2 -of lavf -lavfopts format=psp -o 5cm_psp.mp4

• mencoder: the encoder that i used
• 5centimeter.mkv: the source file. In this particular case, the MKV container has 1 video steam, 1 audio stream and 2 subtitles (Japanese and Chinese)
• -font c:winntfontsmingliu.ttc: as I want to embed the Chinese subtitle into the output, I specified the MingLiu font here
• -subfont-text-scale 3: scale down the font for PSP's relatively small screen
• -vf pullup,softskip,dsize=480:272,scale=0:0,harddup,unsharp=l3x3:0.5: video filters. Pullup and softskip are not that useful here as the original source has frame rate of 23.976 already. Dsize and scale are to resize the video. Hardup ensure all frames are processed and finally apply an unsharpen mask.
• -sid 1 -slang chi: embed the Chinese subtitle
• -ofps 24000/1001: output fps is 23.976
• -oac faac -faacopts br=128:mpeg=4:object=2:raw -channels 2 -srate 48000: audio part. Uses the AAC codec, 128kbps, mpeg 4 compatible, 2 channels, and sampling rate is 48kHz.
• -ovc x264 -x264encopts bitrate=500:global_header:partitions=all:trellis=1:level_idc=30:threads=2 -of lavf -lavfopts format=psp video part. Uses X.264 codec. Trelllis, and level_idc are for fine tuning the quality. Threads=2 is used because my PC has 2 cores.