Confirmation of OU devices and claims

[tomd]

Ringing a LCR circuit with a square wave. Its important the frequency of the source is sufficiently less than the resonant frequency.
"Why is ringing occurring here for square-wave inputs at only low frequencies?

Because it's not low frequency - the edge of the voltage (if infinitely steep) has contained inside it infinite harmonics and, one of those harmonics will be coincident with the LC resonant frequency and trigger a damped oscillation as seen in the 2nd waveform picture. Of course, the edge of the voltage only has to contain a harmonic coincident with the LC resonance for this to happen - it doesn't need to be infinitely fast." https://electronics.stackexchange.com/questions/259593/a-question-about-ringing-phenomena-and-resonance

[AlienGrey]

https://www.youtube.com/watch?v=AQqYs6O2MPw

Walter Lewin a real 'fun guy' he must get it from the mushrooms he eats. 

Also Itsu yes made up your circuit as I have used resonance many times but never tried to test for 90 deg till now! as many of will already know I will repeat the obvious fact 'to get a phase shift of 90 deg both a capacitor and the inductor to have to be in resonance' with your selected 'resonant throughput frequency'!

Well, that solves one problem and explains a great deal! 
Many thanks all!  AG

[itsu]

It seems bigger is better in this case.

So i build a big coil with what i have:

former 16cm diameter
1mm diam wire (AWG #18)
145 turns spanning 15.5cm, so coil is almost square.

Measured:
Inductance 2.3mH and Q 98 @ 100Khz
DC resistance 1.7 Ohm

Series capacitor is 2x 35-345pF air variable paralleled.
Measured:
51-684pF.

Resonance tuned to 180Khz (caps slightly below half way).

Using my FG only in square wave DC 50% duty cycle 10Vpp:
picture shows this setup.
screenshot shows first results:

Yellow: voltage across C
Green: current through LC (inverted so it shows the voltage leading the current as in an inductive circuit)
Blue : input voltage from FG
Red:  math trace yellow x green = real power in the LC circuit.

So allthough we have a high p2p voltage across both L and C, the 90° shift between voltage and current accounts for the low power.

Itsu

[itsu]

I added the gate driver running at 9V (60ma), see screenshot.

Yellow: voltage across the air caps
green: the current through the LC circuit
blue: voltage from the gate driver out.


I tried to modify my satellite LC coils (163uh @ 100pF) by paralleling a 4.7nF cap to the 100pF trimmer so
they would resonate also around 180Khz, but that won't work.

They strongly try to resonate around 2.8Mhz which seems to be their natural selfresonance frequency, so all
i see is a ringdown on 2.8Mhz repeated every 180Khz.
I guess the LC relationship is way off to be able to resonate that low.

Also my hall sensor probe seems unable to correctly pick up the signal, its always is showing a one direction
magnetic field (@ 180Khz) no matter how i keep the probe toward the coil (front, rear or side).
It does show stronger amplitude at the top of the coil (same as my field strength meter). 

Itsu

 

[benfr]

It seems bigger is better in this case.

So i build a big coil with what i have:

That's an awesome setup itsu. Congratulations. I can see you went for the big coil as presented by Rick on his video. It is looking like it.
1. Do you have voltage loads like bulbs/LEDs to light at resonance with the small input ?
2. Did you buy the gate driver somewhere or you built it ? I am interested to know about the schematics if you please.