[Lowfer] Epson Question

[Bill de Carle]

At 04:41 PM 4/18/2004 -0700, Stewart, KK7KA wrote:
>Hi all,
>
>There is no need to argue -- both Bills are right, but are describing
>different quantities.  Bill de Carle's formula of V^2/2*R gives the total
>power delivered to a load, when the signal switches between V and ground,
>with a 50% duty cycle.  However, half of that power is DC, and would not
>contribute to radiation, drive power for an amp, etc.  Bill Ashlock's
>formula of V^2/4*R gives the total AC power in the square wave.  However,
>that also includes the harmonics, which are not useful HiFER output.  IIRC,
>the p-p amplitude of the fundamental is ~1.275 times the p-p of a square
>wave.  Then, applying V^2/8*R, where R is the effective load resistance at
>the fundamental frequency, should give a reasonably accurate result.

Very clearly stated, Stewart!
I was trying to get some discussion (argument?) going to liven things
up a bit.  We often fail to define precisely what the conditions are
when tossing formulas out, which can lead to erroneous assumptions.
Bill was no doubt right in using the term square wave to describe a
signal that is a limiting case for a clipped sinewave, i.e. one which
spends half its time above ground, the other half below ground, with
the load connected to ground.  My beef was that there are other cases
where the driving signal is a "square" wave, shape-wise, that don't
have the same power delivered.

Bill