Radio913 wrote:
wrote in message ...
Its not. Its 3.8 volts, which is entirely consistent with circuit
theory and 'classic' rho. Not only is it higher than the incident
voltage, it is higher than the source voltage.
Ok, now take the capacitor off, and measure the voltage at the end
of the inductor. What do you get?
Not possible for me. My scope probes are in the order of 15 pf, which
is signifcant for this experiment.
Afraid to measure it, eh? Go ahead, we can ignore the 15 pF for now, as
the load was 100pF. What do you get?
You asked for an open. 15pf is about 1000 ohms at 10 Mhz. This is a long
way
from an open. In any case, I suggest it might be your turn to produce
some
experimental results.
But try using classic rho and revised rho to predict the results for
a shorted load (Zl = 0). Only classic rho gives a reasonable result
for voltage and current.
Classic Rho gives -1, which is a short, and conjugate Rho gives
+1j, which is ALSO a short.
As I recall, the purpose of rho was to compute the reflected voltage so
that net voltage could be computed using:
Vnet = Vfwd + Vref
Using rho = -1 produces Vref = -Vfwd yielding Vnet = 0 as expected for
a short.
Using rho = +1j produces Vref = +1j * Vfwd which does not produce
Vnet=0.
This is not the expected result for a short.
Note that the success and failure above are independent of the actual
value of Vi.
Although when I compute rho using the revised formula for the experiment
being considered I obtain rho = 0.885 + j0.464 = 1.0 /_ 27
rho = (Zl-Z0conj)/(Zl+Z0conj) = -(34-j138)/(34+j138) = as above
Has a new revised definition for rho suddenly appeared?
Hint: What is the center of the Smith Chart when it is normalized
to Zo=50+j200?
Not really. A rho= -1 means something else with a complex
Zo.
Hint: What is the center of the Smith Chart when it is normalized
to Zo=50+j50?
Let's review. Two competing proposals (classic and revised rho) were
used to predict the outcome of an experiment. The experiment was
performed; the results resoundingly in favour of classic rho.
I disagree. You need to answer the "hint" question.
I invite you to demonstrate an error in the logic, the evaluation,
or the experimental results.
Riddles just do not cut it.
Plus, you never measured the Vi (incident voltage wave) coming out of the
inductor, which is what you would use for the voltage RC.
Are you questioning the scientific method or just the results of
this experiment? If the former, the discussion should probably
move to a different group; if the latter, you are invited to
replicate the experiment and demonstrate that an error was made.
I question your methods and your calculations.
Feel free to point out the flaws. If you can find none, question why
you hold so tenaciously to revised rho when it does not work.
I will try the experiment when i get the chance.
Excellent. There is nothing better than seeing it with your own
eyes.
Are you saying that a capacitor can reflect a RMS voltage wave that
is greater than the incident voltage wave that charges it?
That is the result of the theory and of the observation. What more can
one ask for? (And since the circuit is resonant, it should not really
be a surprise).
....Keith