Re: Zener Diode for air core binary primary

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Jan Wagner <jwagner-at-cc.hut.fi> 


On Mon, 3 Nov 2003, Tesla list wrote:
 > Original poster: Harvey Norris <harvich-at-yahoo-dot-com>
<huge snip>
 > How many cycles does it take for the source resonant
 > frequency circuit to reach its fullest voltage rise?
 > Surely this does not occur in merely one cycle.

Depends on too much - measuring would be the best way to find out these
times for your setup, IMHO.

 > Let me digress somewhat further on the construction of
 > my primaries. They are ordinary 14 gauge coils of 500
 > ft on spools,~ 11 mh; obtainable at a hardware store.
 > In isolation they will resonate at 480 hz using 14 uf,
 > giving a decent q factor of around 17, for the
 > application I might wish to use. This means that when
 > they reach series resonance, the internal voltage rise
 > has risen 17 times what the alternator source of
 > voltage provides. But again I wish to understand what
 > time period is involved there for them to reach that
 > fullest voltage rise. So here I am contemplating the
 > use of a zener diode and scope to determine what this
 > time period might be.

You could just check the period using for example a HV probe (maybe a
simple resistor divider network) on a scope...

 > The reasoning for this is based on an experiment I did
 > that determined the following: the polarity of the
 > primaries magnetic fields in series resonance is
 > opposite to the polarity of those fields made in
 > parallel resonance. This means that if I have a
 > mechanism for instantly converting and making a
 > polarity change, the magnetic fields from the
 > primaries will be moving much faster through space to
 > get to the opposite polarity than what they ordinarily
 > move at when functioning at the source frequency of
 > 480 hz. Faster magnetic field movement through space
 > should translate to better effects on the air core
 > secondaries themselves.

Sounds dubious, the fields don't move faster than they did before, they
still move at c. Got any simple schematic or drawing about your setup?

Adding two 90deg phase shifted 480Hz signals merely results in a 480Hz
signal of different phase and amplitude. This might not be what you want
to achieve?

Also, the magnetic coupling between the two coils should cause some
unexpected probs. After a very short think I'd picture the resulting
resonant freq of the two coupled oscillators to end up lower than 480Hz
(if they oscillate freely, not driven by one alternator)

 > So having tried to explain the primaries construction,
 > and why I use two of them to give this resonance
 > switching option: my question becomes fairly simple,
 > why couldnt I use a diode that only turns on after a
 > specific voltage is reached,
 > and I understand that a zener diode does exactly that function.

Not really, it only clamps the voltage:
   http://www.americanmicrosemi-dot-com/tutorials/zener.htm
i.e. a 18V Zener starts to conduct current if the reverse voltage goes
over 18V, but there's still ~18V accross the diode, causing
   18V * reverse current = zener diode power loss (heating...)

You could use a beefy diac, however. They break down at a high voltage,
after which they have a very low forward voltage and can conduct high
current pulses without too much loss.

If you need to conduct current into only one direction, you can replace
the diac with a high voltage transistor and some additional circuitry to
switch it on/off at specific averaged coil-voltages.

cheers,
  - jfw

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