Contents
  EIRP Chart for Windows Help

What is EIRP Chart?

How to use EIRP Chart

Valid User Entered Data

Disclaimers & Warranties


  What is EIRP Chart?

EIRP Chart for Windows, in it's simplest terms, is an electronics calculator that consolidates both Ohm's and Watt's laws into one easy to use interface.  The formulas, familiar to professionals in the field, allow you to calculate the unknown electrical properties of a circuit.  Let's say you had a light bulb with a resistance of 3 ohms connected to a 12VDC battery and you wanted to know the current draw of the circuit.  Using Ohm's Law, the answer would be 4 Amps.  What if you wanted to know the power consummed by the device? (in this case, a light bulb).  Using Watt's Law, the answer would be 48 Watts.  Using EIRP Chart, all you have to know is two of the properties and the program will calculate the others for you.  You do need to have a basic understanding of Electricity or Electronics however.  This program, while a great learning aid to students, will not teach you Basic Electricity or Electronics.  See the Warranty & Disclaimer Section in this manual or within the program before proceeding.


How To Use EIRP Chart
  How to use EIRP Chart:

In the main display of the program is a group of square icons that display the formulas used to calculate the unknown properties.  These graphical controls, similar in appearance to the old "PIE" charts, are sub-divided into four seperate sections, each associated with finding a particular value.  They are titled as such:

E =	Voltage in Volts

I  =	Current in Amps

R = 	Resistance in Ohms

P =	Power in Watts

So, if you are trying to calculate the value of the voltage, you need to select one of the formulas in the "E" section.  If you know the current and the resistance, for instance, you would pick the control in the top-left corner.  After clicking on the formula control with the mouse, a "Value Requester" will appear prompting you for the current and resistance values.  After entering the values, and pressing the Return key or the "OK" control, the program will calculate the other two unknown values and display them in the display boxes on the main program window.  Whether you use the Mouse or the Keyboard to control the program is entirely up to you.  You can choose any of the menus by using the Keyboard by holding down one of the Alt keys (on the Keyboard) and selecting the underlined letter in the Menu Name.  For example, to access the About menu, you would hold down one of the Alt keys and select the letter "a" on your keyboard.  Also, all of the controls are accessable in the "Value Requester" via the Keyboard.  Here is a list of the keys and their mouse equivalants if applicable:

TAB =	Selects a Control in normal order

SHIFT + TAB =	Selects a Control in reverse order

RETURN =	OK

ESC =	Cancel

Notice that if you select a formula and then select "Cancel" with the Mouse, or hit the Escape Key on the Keyboard, the calculations abort and the program will still display the results from the previous calculation.  This is particularly usefull if you accidentally select a formula, before noting the value of the last calculation.


Valid User Entered Data
  Valid User Entered Data:

Only a valid number can be entered into each requester box when selecting a formula.  The number can contain one decimal point, or be in Scientific Notation.  It also can be a negative number, except in the two formulas using the square root function.  The number cannot be zero, as the number must have some value.  The number cannot contain letters, except in the case of Scientific Notation.  For example, the following expressions are valid:

1.65E+11	:Equivalent to 1.65 X 1011

2.434E-102	:Equivalent to 2.434 X 10-102

Notice the capital "E" in the preceding examples.  This letter MUST be a capital letter, as a lower-case "e" will not be accepted.  Here are some more valid expressions:

300

-1.62

.001

0.000002

There are limits to how big or small the number can be however.  Due to limits of the language in which this software was programmed, the values must fit into the following range:

+-4.94 X 10-423 through +-1.79 X 10308

Also, the numbers are limited in precision, or the amount of significant digits, to roughly 15.  So, the following number:

1234567890.123456789  would be expressed as

1234567890.12345


Disclaimers and Warranties
  Disclaimers and Warranties Section

THIS PROGRAM IS BEING MADE ON AN "AS IS" BASIS, AND CARRIES NO WARRANTIES, EITHER EXPRESSED OR IMPLIED. The author shall in no way be held responsible for any damages resulting from the use of this product, or from the media in which it is being distributed, including without limitation, loss of business profits, interruption of business, damage to equipment, or any other incidental or consequential damages.