[NewCandle] SEC

[Keith Nagel]

Hi gents,

Ferrite cores for AM antennas are typically Manganese-Zinc ferrite.
This is a low frequency, higher permeability material. Q's for
resonators made with this can be in the nabe of 1000, more if you're willing
to anneal the piece yourself. 

The problem with stacking N LED's in series is that once one
fails, the whole of the voltage is then impressed on N-1
LEDs. It's easy to blow the whole chain if you've got one
weak link. 

>The voltage rise is curious, since for instance, with a 9 volt in a 4-1 
>turns ratio - you can end up with 125 volts in operation, instead of the 
>expected 36 due to 'resonant rise' which occurs in the feedback.

Now Jones, I'm sure if you measured the Z and Q of the secondary,
you'd find the ordinary laws of RF are being obeyed (grin). 'Course
if you want to apply those awful circuit theory simplifications
( like turns ratios ) you're going to be scratching you head
over these things for a long time...

You know what would really help, Nick? Take a function generator,
some signal diodes, and a couple LEDs, and make lighting efficiency
measurements comparing pure DC and rectified AC at the frequencies
in question ( 2MHz to 12MHz ). I think that one measurement would
at this point either pass or fail the entire concept. If there
is a difference, then there is something to hang your hat on
at least. Otherwise, I am just not seeing anything mysterious here.

That said, making the current measurement will be difficult.
Are people really using current sense resistors? That's folly.
Do you have a good HF hall probe, Nick? 

K.