Please Read First
Written by Bryce Ringwood   


I have changed this section so that people familiar with electrical components and calculations will feel more at home (possibly!).

The idea is that you can now express component values, such as resistance with a familiar suffix, i.e 10 Megohms = 10M and can be input as such.

Here are the standard suffixes (suffices??) for SI units.

    SI Prefix Abbreviaton          SI Prefix          Multiplier
 P Peta 1 000 000 000 000 000
 T Tera 1 000 000 000 000
 G Giga 1 000 000 000
 M Mega 1 000 000
 k kilo 1 000
e    See text!
 m milli 1 / 1 000
 u (for "mu") micro 1 / 1 000 000
 n nano 1  / 1000 000 000
 p pico 1 / 1000 000 000 000
 f femto 1 / 1 000 000 000 000 000
 a atto 1 / 1 000 000 000 000 000 000

Table of Common SI Abbreviations

There are other units, such as "Exa", which I didn't include. Confusingly, you will see resistors marked 1e5 or 1r5, meaning 1.5 Ohms. If you enter 1e5 into the edit box, it will be interpreted as 1.5 (Try it) BUT if you enter 1E5 - the program will think you are using eponential notation (Try it). 1r5 DOES NOT WORK - it is the old way of marking resistors.

Note that you can enter 1M8 - meaning 1.8Meg(Ohms or whatever).


Enter a value                 

See how it is interpreted

Try Box


Things that are not physical quantities

Things like turns ratios an numbers of turns are just arbitrary numbers - and enter them as such. You can enter them with the above suffixes. I suppose a kiloturn is a thousand turns, but they will be output as numbers in scientific notation.

Why do it?

I am trying to make the input follow consistent rules, reduce typing and mimic the values printed on the components. You may find other programs like ltSpice follow similar input rules. The section is (possibly unfairly) targetting engineers and engineering students, as well as hobbyists with an engineering background. Let me know how you get on.

The equations in the "theory" section

With the exception of the reactance chart, the equations are generated by jsMath, a mathematics text processing system. I would have liked to use MathML, but I can't get Internet Explorer to decipher it. jsMath puts a red banner at the top of the section, inviting you to download fonts. It still works (more slowly) if you don't download them.

Source Code

Is available. Contact me, as the source may not be available from the "view source code option" in your browser.



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