Confirmation of OU devices and claims

[lancaIV]

Low power circuit device :
https://www.mdpi.com/1424-8220/19/9/1963

[seaad]

Itsu
Ahaa! Ok. Then you can adjust the output resistor for best power and Q match.

But I assume that the voltage at the output is relatively small (but high Amp ) so You will loose much power in the diode bridge.

For best output match I rceommend a parallel circuit. Connect the bridge across the whole P-circuit and use a load resistor of a much higher value than 50 Ohms.
Now the bridge plus looad is not affecting the result and Q so much.

PS. lancaIV Thumbs up!

Regards Arne

[seaad]

Low power circuit device :
https://www.mdpi.com/1424-8220/19/9/1963

[Vortex1]

Dear seaad

Thank you for the nice graph, which clearly shows the difficulty in getting high power transfer and overunity with loosely coupled coils.

Giving your impedance matching scheme some thought, it seems we are always in danger of blowing out the output stage on some of the lower cost generators, regardless of which direct drive scheme is used, current injection without matching transformer the circulating current can get large enough to fry the output stage. With impedance matching transformer, the voltage will get high enough to do damage.

All of this assumes the Q of the resonating system is very high. Better generators will include protection to limit current or clamp voltage.

Also, fortunately the internal 50 Ohm resistor will help to preserve the generator. I sometimes use a small incandescent lamp on the output of the generator for extra protection against over current or an external buffer stage.

FWIW
Regards

[gyulasun]

Low power circuit device :
https://www.mdpi.com/1424-8220/19/9/1963

Hi lancaIV.

Thanks for the interesting link. 

For those members here who may need some more hints on what the relay resonator does:  its effect is very similar
to the role of using one (or more) antenna elements in a Yagi type antenna for instance. 
Say there is a two element Yagi antenna and a 3rd element is added, this way the antenna gain increases
in the main radiation direction. 
This means that this now 3 element antenna (fed by the same amount of input power) will insure higher field strength 
in the main radiation direction than the 2 element antenna insured previously (measured at the same given distance), 
while radiation will be decreased in most other directions. 

Here are two referenced articles from your link.  In the first link, Figures 12, 13 and 14 include measured 
energy transfer efficiencies.  Full paper text is available for payment only, unfortunately.   
https://www.semanticscholar.org/paper/General-Analysis-on-the-Use-of-Tesla%27s-Resonators-Zhong-Lee/6e41afe4ff78a0964106f076134b46417f3d7b0d 

EDIT: I found almost the same paper from the same authors above, this one is freely available here: 
  https://core.ac.uk/download/pdf/37985578.pdf     

Another referenced article discusses several aspects of wireless energy transfer, including efficiency too. 
This quote is useful here:     (WPT=Wireless Power Transfer)
"... Figure 3 shows the transfer efficiency of the different WPT techniques for near and far fields.
The inductive coupling technique achieves an energy transfer efficiency of 70–90%; it decreases with the
distance between primary and secondary coils. To perform such a high efficiency, accurate alignment between
primary and secondary coils is required [57].  Magnetic resonant coupling technique has a medium efficiency of
40–60% and also decays with distance. ..."

Here is the full paper:   
https://www.mdpi.com/1996-1073/10/7/1022/htm   

Gyula