Power measurement in resonance

[andy]

I am studiing similar circuits from D. Smith and I discovered this patent, where are similar circuits as in Zilano

https://patents.google.com/patent/KR20110139558A/en

I guess that one of the main points is that spark gap (or GDT or maybe tunnel diode) acts as negative resistance in resonant circuit.

[Sandy]

LT spice. Blue is power on voltage source. Green is power in inductor. Open source, let's get it!
Kind regards, Sandy

Sorry this is not what I thought. The negative side of the power in the inductor cancels the total power if a resistor is placed in series with the inductor.
Kind regards, Sandy

[kloakez]

LT spice. Blue is power on voltage source. Green is power in inductor. Open source, let's get it!
Kind regards, Sandy

Hi Sandy,

I am not an expert in these tools but I think the order of parts matters too. And personally I'd arrange the parts like so:
   
Mainly I'd put the ground on the - or "minus" branch of the voltage source as you need a reference. The usual equation for computing resonance doesn't work in this case, since there is one more capacitor and the circuit that you put together would have resonance frequency at 45 Hz. That is an easy fix. The equations that need to be used for this circuit are:
   

Maybe you just made a mistake, I sometimes spend whole evenings on mistakes like this Guests cannot see images in the messages. Please register at the forum by clicking here to see images.

And with LT spice it is possible to do a sweep like this:
   
Which looks closer to 50 Hz. I put R2=13 ohm as that would be a value of a 4 kW heating element, which is just an arbitrary value.

And if I look at the input/output power, then it looks quite unbelievable. The input power which I compute as the voltage drop over the resistor multiplied by the current going through the resistor turns out to be about 20 W? And the R2 power about 1kW. So I am assuming I made a mistake somewhere or several of them.
   

[kloakez]

I am studiing similar circuits from D. Smith and I discovered this patent, where are similar circuits as in Zilano

https://patents.google.com/patent/KR20110139558A/en

I guess that one of the main points is that spark gap (or GDT or maybe tunnel diode) acts as negative resistance in resonant circuit.

Interesting! I have enough parts at home to build circuits like this. But what I tried didn't work, so I am starting with easier circuits and try to build from there. Don Smith said he can simulate his circuits and they show the gains he reported. I even looked for the program he mentioned at the Spanish institution using the wayback machine and found out the simulator he used is part of some other company's solution, forgot the name. But it would be pretty sweet to simulate spark gap to see how it is working, maybe there are SPICE models available.

Looking at the patent, there are some pretty obscure parts, radioactive materials? round capacitors with specific size and distance? But maybe they are not needed to make it work.

Just found an voltage-current characteristic of a GDT. It seems to me the the i3 to i1 current increase before a spark is the negative resistance region. So what does one need to do to make the best use of it? Do you know?
   

[kloakez]

So I tried the configuration from Tesla's Colorado springs notes with the three capacitors. In practice I just added another capacitor of the same value at the black/ground electrode.

   

I set the signal generator to its maximum setting 20 V since I have measured the maximum power deliverable by the generator to be 0.5 W and wanted to see what power will there be on the R37.

   

So the voltage drop on R36 is 603 mV and on R37 it is 1.64 V RMS. That gives P_R36 = 363 mW and P_R37 = 2.69 W. Which should not be possible. Of course there can always by measurement error. The simulations I get from Ansys differ from simulations I get from LTspice and they both differ from measurements in this case.

This guy says he uses this configuration of coil and three caps:
https://www.youtube.com/watch?v=Ya2sqVvc9TA
https://www.youtube.com/watch?v=jAL4pByUn2U