Kapanadze Cousin - DALLY FREE ENERGY

[verpies]

I did some testing with my transistor KT926A driven by the MOSFET driver UCC27511 (sink R= 11 Ohm/source R=14.7 Ohm).

Questions:
Is your test setup like on the schematic attached below, except for Q1 being the BJT ?
Is your Flyback Diode (D1) burned out? - I thought I saw the current in the CSR reach large negative values and voltage spikes on the base.

Objections:
Shorting W1 in this setup is dangerous because up to 300A can flow through the 0.1Ω CSR at 30V (+V2), and the KT926A can withstand only 15A.
In the previous setup, it was OK to short W1 up to 150V because you had a 10Ω Load Resistor in place of R3 (also acting as a CSR).

Also, the DSR Diode requires forward pumping pulses around 200ns - not 765ns. See this thread.

Finally, the voltage across your 0.1Ω CSR (R3) is reaching 5.2V.  That means that 52Amps are flowing through it !!!  (because I=V/R and 5.2V/0.1Ω=52A).
The KT926A cannot conduct this kind of current (especially at those base currents) so this means, that:
1) either there is some kind of a mistake, or
2) the CSR (R3) is inductive, or
3) your scope ground lead is forming a loop that is picking up stray flux from T1,
4) ...or you have beta current in T1 stimulated by NMR

Re. Pt.3: What happens when you eliminate your scope ground lead like this ?


Suggestions:
Fix the current measurement error in the collector subcircuit before you attempt to observe the saturation of T1.

[itsu]

Questions:
Is your test setup like on the schematic attached below, except for Q1 being the BJT ?
Is your Flyback Diode (D1) burned out? - I thought I saw the current in the CSR reach large negative values.

Yes, that was the test setup.
I hope not! :-)   I will have to check on that.  EDIT (flyback checks out to be ok, also compared to a brand new one).

The KT926A cannot conduct this kind of current (especially at those base currents) so this means, that:

I bet my money on: 2) the CSR (R3) is inductive.
However, the spec's on this CSR says:

F E A T U R E S
• Ideal for current sensing applications
• 1% Tolerance standard, others available
• Low Inductance (non-inductive below 0.25Ω)

What happens when you eliminate your scope ground lead like this ?

I will have to check that tonight.


Regards itsu

[verpies]

F E A T U R E S
• Ideal for current sensing applications
• 1% Tolerance standard, others available
• Low Inductance (non-inductive below 0.25Ω)

They might be writing the truth, because shorting W1 should increase the current through the CSR yet at 9m26s of the video the signal across the CSR is decreasing significantly after shorting W1 !!!
(I can't see Ch1's V/div, thus I can't write - to what level).

Think about it.

P.S.
Fortunately the max 816mA current supplied by the USS27511 driver to the base of the KT926A (because 12V/14.7Ω=816mA) prevents the transistor from fully saturating during this large "shorting current", thus the lack of the 10Ω resistor in the collector circuit, is mitigated.
If this base current was larger, then the collector current of the KT926A would exceed the max 15A and this transistor would be toasted.

[verpies]

I bet my money on: 2)

My money is on Pt.3

[itsu]

(I can't see Ch1's V/div, thus I can't write - to what level).

At 09:48 in the video you can see the ch1 setting to be 500mV/200nS per division, which means roughly that 5A is running for 765nS through the csr when i shorted L1.

So this is the max. current limited by the base resistor which means that the earlier measured 52A must be in error like you said.

Will see tonight.

Regards Itsu