To use Calculators here, your excel must have the following.

1       Analysis Tool Pack Add-in has been installed.

To install the add-in,
Click "Tools" in Menu Bar.  
Click  "Add-Ins" to open Add-in Dialog box.
Select "Analysis Tool Pack".  
Click "OK" button to close the Add-in Dialog box.

How to Install Analysis Tool Pack

2        Security Level must be medium.

To make it,
Click "Tools" in Menu Bar.  
Click "Options" to open Option Dialog Box.          
Click "Security " tab.  
Click  "Macro Security" button to open Security Dialog box.  
Select "Medium" radio button.  
Click "OK" button to close the Security Dialog box.
In Option Dialog box, click "OK" button to close the dialog box.

How to change security level

3        When you open the files, you may be asked whether disable or
enable macros, select "Enable Macros". If you are not sure the files are
safe from a macro virus, scan them with your anti-virus software before
opening them,
My Calculators
Download Complex Chain Calculator   To calculate complex

Download a very simple tutorial

Download Complex MathCalc   (Updated 7 Aug 08)
To calculate complex numbers,  bridge currents, simultaneous

Download Vdrop   For cable voltage Drop and short circuit

Download Symcom01 For symmetrical Components
calculator (Uploaded 4 Sept 08)

The followings are not calculators but maybe interesting.

LR and RC Transient  To see the transient wave form in LR
and RC circuit.

Pythagorean Theorem  To prove Pythagorean Theorem.