[R-390] Ballastubes (was inrush current limiters)

[Drew Papanek]

On Mon, 23 Dec 2002 21:58:34 -0600, Cecil Acuff wrote:

<snip>

>An AC waveform is a Peak to Peak waveform.  Moving equal amounts above and
>below Zero.  (in this case)
>
>You arrived at peak value by half wave rectifying the Peak to Peak sine
>wave.

Half wave will posess the same (neglecting diode drop) peak value as the 
symmetrical sinewave whence it came, but a half sinewave is not the same 
waveform as a full sinewave.

>You now multiply that value by .707 to get the RMS value.  To go from
>RMS back to Peak you multiply by 1.414 and then double that to get Peak to
>Peak values.

This applies to a full sine wave, but not a half sine wave.  Yes, the RMS 
value of a sine wave is .707 times its peak value.  However, the RMS value 
of a half sinewave is .5 times its peak value.

Drew

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