சுதர்சன் சாந்தியப்பன்

So, for this configuration you need a 1250VA Inverter with 2x12v 100Ah battery bank.  Let me explain the calculation,

1. Power Factor: In AC (alternating current), Power = Voltage x Current x Power factor unlike in DC, Wattage = Voltage x Current.  Power factor is measure as the cosine of the phase angle between voltage waveform and current waveform.  For home use, the power factor will be 0>PF<1.  When PF is lower, the efficiency of the system suffers a lot.
2. Battery Voltage: For 1250VA inverter system, the choice of battery bank is 24V instead of 12V.  The rationale for this choice is to limit the current from the battery to the inverter unit.  If you use a 12V battery bank, at full load there will be a current of 1250/12=104A flowing from the battery to the inverter.  You may have noticed the thickness of the battery wire be very high.  Despite that the power loss on those wires when the current is 100A, would be much higher than it is with 50A on a 24V system.  For a 24V system, the peak current shall be 1250/24=52A.  Also, at 100A, with 1m cable between battery and inverter, the impedance should be 0.00001 ohms.
3. AH Margin: Although battery AH rating considers absolutely draining of the battery, we will not be able to do that for normal SMF battery.  Meaning, we should not discharge below 10V and likewise should not charge beyond 13.6V per 12V battery.  In order for the AH rating to work, we have to apply atleast 20-30% margin.

LM35 Temperature Sensor

The System.

The monitor.

The mixed water line:

The hot water line:

The cold water line:

monitor opened up:

the atmega8 microcontroller

the lcd unit:

theboard:

inside the monitor:

The AVR code.

const int COLD = 0, HOT = 1, MIXED = 2, CALIBRATE = 3;
const int PWMPORT = 5;

float SCALE = 5000.0/1024.0; // 10 bit resolution for ADC
const float LM35SCALE = 10; // 10mV per Centigrade

#include <LiquidCrystal.h>

LiquidCrystal lcd(13, 12, 11, 10, 9, 8 );

byte smiley[8] = {
  B00010,
  B00101,
  B00010,
  B00000,
  B00000,
  B00000,
  B00000,
};

float Calibrate( void )
{
  // write 5v to PWM port
  analogWrite(PWMPORT, 255);

  // read the 5v analog value in the calibrate port
  delay(500);
  int val = analogRead(CALIBRATE);

  // read again the 5v analog value in the calibrate port
  delay(100);
  val = analogRead(CALIBRATE);

  // whatever digital value we read is the range of output that we would get for 5v input.
  // so, set the scale appropriately.
  SCALE = 5000.0/(float)val;
  
  return SCALE;
}

void setup()
{
  pinMode(PWMPORT, OUTPUT);
  
  lcd.createChar(0, smiley);
  lcd.begin(16,2);
  
  lcd.setCursor(0,0);
  lcd.print(“Calibrating..”);
  float scale = Calibrate();
  lcd.setCursor(0,1);
  lcd.print(“Scale=”);
  lcd.print(scale);
  delay(1000);
}

int Temp( int inADC )
{
  float lm35volts = (float)inADC * SCALE;
  float temp = lm35volts/LM35SCALE;
  
  return (int)temp;
}

int ReadData( int port )
{
  int data = -1;
  for ( int i = 0; i < 3; ++i )
  {
    data = analogRead( port );
    delay(100);
  }
  
  return data;
}

void loop()
{
  int cold = ReadData( COLD );
  int hot = ReadData( HOT );
  int mixed= ReadData( MIXED );
  
  int cold_temp = Temp(cold);
  int hot_temp = Temp(hot);
  int mixed_temp = Temp(mixed);
  
  lcd.clear();

  lcd.print( “C=” );
  lcd.print( cold_temp );
  lcd.write(0);
  lcd.print(“C”);
  lcd.print( ” H=” );
  lcd.print( hot_temp );
  lcd.write(0);
  lcd.print(“C”);
  
  lcd.setCursor(0,1);
  lcd.print( “Mixed=” );
  lcd.print( mixed_temp );
  lcd.write(0);
  lcd.print(“C”);
  
  delay(1000);
}

This write up is taken from http://www.engineeringtoolbox.com/wire-gauges-d_419.html

The AWG table below is for a single, solid, round conductor. Because of the small gaps between the strands in a stranded wire, a stranded wire with the same current-carrying capacity and electrical resistance as a solid wire, always have a slightly larger overall diameter. The higher the number – the thinner the wire. Typical household wiring is AWG number 12 or 14. For telephone wires there are common with AWG 22, 24, or 26.

The higher the gauge number, the smaller the diameter, and the thinner the wire.  Because of less electrical resistance a thick wire will carry more current with less voltage drop than a thin wire. For a long distance it may be necessary to increase the wire diameter – reducing the gauge – to limit the voltage drop.

This was the original design of the solar panel mounting structure.  Later, I had simplified the design and fabricated them at the local metal fabricators.  Please click on the images to open the big sized drawing.

Pole that would hold the weight of a heavy solar panel over a base structure (not shown).

Hinge design that would transfer the weight from the base structure to the pole, with one degree of freedom.

The completed Solar Panel mount structure.

Bottom side view of the panel.  The Panel is fully resting on the Iron frame constructed in the nearby fabrication shop based on my design.

This is my assistant Aakash, the boy next door.  He has been my aide for all the mechanical and automobile works.

The base frame of 30″ x 21″ with the center piece at 15″.

The base frame from perspective projection.  The center piece is a 5″ x 2″ 10mm plate welded at the center.  The holes are 10mm diameter drilled at 1″ and 3″ from the top and centered.

The main load bearing vertical pole measuring approx 2m and 2″ diameter.  The base plate is 6″ in horizontal length and 6″ on vertical depths.  The holes are 1/2″ and drilled at 3″ and 5″.

This is the solar panel bought from Akshaya Solar Pvt Ltd, AP.  The panel is rated 12v 70w and of dimension 1200mm x 21″ and weighting approximately 5kg.

The swing arm connecting the base frame and vertical pole.  The holes are 10 mm diameter and punched at 1″ and 3″ from the top.  The bottom pipe is 2.25″ diameter and about 5″ long.  The cross bolt is 0.5″ diameter.  This swing arm mounts on the pole on one side and attached to the base frame on the other side.  The base frame is pivoted on the top hole with swing setting using one of the 3 bottom holes.  The positions are provided to compensate of uttrayanam (north bound sun movement) and dakshanayanam (south bound sun’s movement).

The bottom link of the vertical pole.  This U link attaches to the parapet wall, which is 6″ is width and the cross bolts pass through the wall to lock the vertical plates.  The horizontal and the vertical plates are 6″x2″ and 10mm in thickness.

These are the bolts used.  The 1″ (4 nos) bolts are used to secure the solar panel on the base frame.  The 1.5″ bolts are used to secure the base frame to the swing arm.  The 4″ bolt is used to secure the swing arm to the vertical pole and the 8″ bolts are the bolts to secure the entire unit on the parapet wall by passing through the wall.

White (Blueish) LED strips with 3M water proof stickers are available for 300-350Rs/30cm.  These LED strips are pretty bright when illuminated and draws lesser power when compared to incandescent lamps.

Step 1: Open the Bonnet of the Car

Step 2: Identify the Parking Lamp + Head Lamp Positioning Motor Power Line

Step 3: Remove the Parking Lamp, Lamp Positioning Motor Power Connector

Step 4: Remove the Connector Shield to find the Power lines

Step 5: Find and Tap the Parking Lamp Line.

Step 6: Put the connector shield back on the connector
Step 7: Put the connector back on the Lamp assembly
Step 8: Turn on Parking Lamp; Hurray LED Strip is AWESOME.

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If you are an exclusive BSNL broadband user, you might not have attached the telephone to the phone line.  I have connected my Netgear modem to the DSL/Phone line splitter and left the other connection floating.  Lately, when I noticed that the Netgear modem was not able to make the connection with BSNL servers, originally I thought the telephone line is dead.  To my surprise the telephone line was fine, but I perceived the lines to be little noisy.  I made a complaint to the BSNL portal and as usual nothing much happened.  Accidently, I had to connect my telephone to the splitter for making a local call.  To surprise, the Netgear modem managed to connect to the server this time.  So, the hypothesis is;

When the telephone line is noisy, attach the telephone to the splitter along with the modem connection to get connected to the BSNL Servers.  Most likely it could be because of the Reactive load offered by the telephone on the phone line ends up conditioning the Phase modulated signals for the Netgear modem to connect to the Servers.

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