Dr Ronald Stiffler SEC technology

[gyulasun]

Hi iQuest,

Thanks for the kind words. I forgot to include this link yesterday on wave reflection simulation,  see here:
http://physics.bu.edu/~duffy/HTML5/reflections.html 
If we choose the "Right end is free" choice at the bottom right instead of the default "Right end is fixed", then we can see the red wave reflects back at the end of the "line",  its positive 20 unit amplitude increases to positive 40 units, then it starts traveling backwards from the open end with the same 20 unit positive amplitude as the blue wave shows. You can pause simulation at time t=0.525 second when the double amplitude is shown developed.  This happens differently when the "Right end is fixed" choice is simulated: no double amplitude at the reflection moment and the returning blue wave amplitude is a negative 20 units (the incoming wave reflected as the inverse of it).

In case of the unloaded L3 coil, or when the "line"  is quarter wave long and unterminated (i.e. we have the "Right end is free" case),  the 'waves' come continuously from a generator (or from a crystal oscillator) and a standing wave can develop at the coil end with a high amplitude. That is what the Doc shows in the two videos as seeking for the maximum RF amplitude around the floating coil end and the frequency belonging to that max amplitude is the coil's quarter wave resonant frequency or as the Doc put it: the Spatial Resonant frequency.
The wave reflection simulation shows 'only' a doubled amplitude when it reflects back at the free end of the 'line' but in case of a coil when it is fed continuously with input energy at the quarter wave resonant frequency (not the case for a quasi arbitrary single wave traveling in the simulation), the resonance not only doubles but enhances the amplitude manifold at the open end (voltage amplification).

We can find the quarter wave resonance in a Tesla coil secondary of course, it makes no difference if the coil is fed by a single wire from a generator or from a few turn coupling coil (that Tesla called as the primary coil).  Recall the Slayer exciter too, the oscillator automatically oscillates at the quarter wave frequency of the coil where the resonant impedance is the highest.
Here is a good read on this topic: http://www.teslaradio.com/pages/tesla_coils.htm 

Thanks and keep the comments coming 
Gyula

[NickZ]

   Guys and Gals:
   I changed the C1815 transistor on my crystal oscillator to a 400v D1300K7-1. I also raised the voltage to the max on my boost converter, 50v. And I was able to get 112v output from my crystal oscillator.
But, this higher voltage transistor is good to 4.000Mhz, only. So, I have to work with a 3.500MHz to 4000MHz crystals that I have on hand. However, for one reason or another the actual brightness of the 10 leds does not change all that much. The leds are placed capacitively. Perhaps the led are the limitation or bottle neck, in this case.
   I still notice that a direct connection to the leds through the AV plug from the L3 coil, provides for a higher output at the bulbs, instead of the capacitive led bulb placement. But, at least now there is NO overheating of the transistor, at all. However, the actual wireless effect is not very impressive, although much better than what I could do before. Still working on all this...

    I will look for the right 120v type led bulb with the aluminum back plate. But, in any case the led bulb is brighter now on 50v than on 12v, but not by that much. Perhaps the 100kohm resistor on the base circuit is not needed now, and a lower value resistor can be used, instead.
   I also added some more turns to my L3 coil, so it's now about 3cm long. But, I may have to add some more turns now, using the 3.5MHz crystal, instead of the 13.5MHz one, to get a better sync from the L3, to the lower value crystal.   I wish that I knew the exact size of mag wire needed to run the L3 at 13.5MHz, or 4.000MHz, as my SG only has a 3v output, and 2MHz limit. So, I can't use it to tune the L3 with. Therefore, I'm still looking for a horse that I can ride...  Along with the right bulb. 
   Connecting the clip lead from the leds back to the negative or positive rail on the battery does improve the bulb brightness, over just the clip lead by itself.  But, the clip lead is still needed, as compared to just a short piece of wire back to the battery.
I believe that the clip lead may also be working as a type of antenna, of sorts. 
   I also tried two crystals at the same time, but didn't have much luck with that idea, so far.
                                   Keeping in touch,                                                              NickZ
   
 

[gyulasun]

Nick,

Nice progress!  Would like to ask you did try the 13.5MHz crystal with this D13007K transistor but it simply did not oscillate?  Or you thought the transistor simply is not suitable due to its 4 MHz frequency limit and you did not test it?

You surely have to increase the L3 coil size for the 3.5 MHz crystal. I suggest to follow what Lidmotor built as a variable coil with a wiper wire sliding on the surface of the coil. Wind a coil at least on a 4 cm OD bobbin with at least a 6 - 7 cm long winding. With the wiper this can be tuned by watching the LED brightness.
When this coil is in resonance, the cliplead from the diode may be removed and the diodes common point may be connected to battery negative or positive, I mean to include the LED board by capacitive coupling into the L3 circuit and tune it by the wiper too.

If you or someone near you has an old, unused AM pocket radio then its ferrite antenna could be taken out and you could use the ferrite rod to tune this L3 coil you have for the 13.5 MHz and lower the coil resonant frequency toward 3.5 MHz. I mean such ferrite rod: https://i.stack.imgur.com/7QaIR.jpg 

Gyula

[NickZ]

   Gyula:   I would call the radio "ferrite rod", a ferrite bar instead. And, yes I have one. It's about 3 inches long, and 1/2 inch wide So I would need to wind a new L3 on a former that is about 3/4 inch OD. So that the ferrite bar will just fit inside the former tube snuggly.
   The led/AV plug can also be used to find the best resonant point on the L3, where it lights the brightest. It works similar to the wipper, to see where the sweet spot is on the coil. Then any extra winds can be removed, as needed.

[TinselKoala]

The ferrite rod (or bar, whatever) works by increasing the inductance of the coil as the rod is inserted more and more deeply. Unfortunately the rod itself will introduce some small losses (decreasing the Q of the system) so isn't the desired way of tuning, if energy efficiency is ultra-important. Better is to adjust turns in the air-core coil. By using the "wiper" method one can determine the number of turns closely, and then another coil can be wound with that many turns but no taps or stripes or overlaps, etc that would reduce Q.

So you have an air-core coil, wound very evenly and spaced evenly. This will have the least inductance and highest resonant frequency, all else being held equal. So inserting the ferrite will progressively increase inductance and therefore lower the resonant frequency. One could wind a coil of too high frequency, tune by inserting ferrite,  lowering frequency until the desired resonant frequency is attained, then carefully remove and measure the ferrite-containing coil's inductance, then wind another pure air core coil to that inductance value.

There are other things that can increase the Q of these systems.