Kapanadze Cousin - DALLY FREE ENERGY

[verpies]

12t   10nF 1723Khz
12t  4.7nF 2463Khz
  6t   10nF 2593Khz
  6t  4.7nF 3663Khz

All had nice peaks on this frequency only.

According to the formula for the LC circuit at resonance L = 1 / (4 * Ï€² * f² * C) now we have:

N          nF        kHz         nH
-----------------------------------
12       4.7      2463       888
  6       4.7      3663       402
12     10.0      1723       853
  6     10.0      2593       377

But something is still wrong, because:

888nH/402nH ≈ 2.2
853nH/377nH ≈ 2.3

...but the ratio of inductances should be close to ≈4 because the turn ratio is =2 (a square relationship)

So I must ask to repeat these measurements with the scope probe set to 1:10 attenuation, and with the signal generator leads as short as possible (soldered directly to the parallel LC circuit via a kΩ resistor in series) and the DUT not connected to anything else.

There must be some huge stray inductance and capacitance or magnetic field that is interfering with measurements !!!

P.S.
What are the OD, ID, TH dimensions of your T1 toroidal core?

[verpies]

At the moment we have little idea of how much current is needed to saturate a toroid of the size and build specified.

...but we need to find out.

Looking at average currents I listed for my setup, rather than extremely short duration peak pulse currents, I cannot see how current at this level is going to heat the core sufficiently to warrant a heat sink as specified by Dally.

I agree, Joule heating (I²R) cannot heat up the windings significantly at these average currents.
What about core heating due to Hysteresis Loss ?

[Black_Bird]

@itsu

When you measure the resonance, you have to add a series resistor of, say, 2.2 k in series with your generator ( supposedly 50 impedance) to have a correct measurement. If you don't do that, your measurements will be masked by the low impedance of the generator. the idea here is to simulate a current source.

[itsu]

What are the OD, ID, TH dimensions of your T1 toroidal core?

Ok, the dimensions are as in post #483  from Vasiliy Buslaev yesterday:

od = 9.5 mm
id  = 5.2 mm
Th = 3.2 mm


@verpies / Black-bird

i normally inductively couple my FG signal into the dut with a single turn winding.
Also now i did so, therefor the FG 50 Ohm impedance will not "load" the dut to much.
Normally this procedure is right on.

Anyway, i will retest tonight using 10 and 4.7nF caps with a 1k and/or 2.2k Ohm resistor in series with the FG.

Thanks,  regards Itsu

[verpies]

OK, the dimensions are as in post #483  from Vasiliy Buslaev yesterday:
OD = 9.5 mm
ID  = 5.2 mm
TH = 3.2 mm

Using the formula for the relative permeability of a toridal inductor with rectangular crossection: μ_r = L / (0.0002 * TH * N² * ln(OD/ID) ) and the formula for the AL Value as A_L = L / N² , now we have:

                    N     OD [mm]    ID [mm]    TH [mm]          L [μH]           Î¼_r        A_L [μH/N²]     Saturation Current [A]
------------------------------------------------------------------------------------------------------------------------------------------
Hoppy         12           11.0            5.0             4.0       312.000       3435          2.167                      ? ? ?
Hoppy           6           11.0            5.0             4.0         88.000       3115          2.444                      ? ? ?
Black_Bird   10             2.0            4.5             4.0           3.500           45          0.035                      ? ? ?
Itsu             12             9.5            5.2             3.2           0.888           16          0.006
Itsu               6             9.5            5.2             3.2           0.402           29          0.011
Itsu             12             9.5            5.2             3.2           0.050             1          0.000                     < 20

Feel free to correct or add to the table above.

Itsu's inductances (0.888μH and 0.402μH) are highly suspect and that's why I marked them with yellow color.

Also Itsu's scope shot of a current ramp 4A/ns @ 200V evaluates to 50nH inductance (marked with red) and with his core dimensions that evaluates to permeability of 1 (the same as air), is strongly indicative of saturation - that's why I wrote that his saturation current is < 20A.