Kapanadze Cousin - DALLY FREE ENERGY

[TinselKoala]

I was thinking about the internal transistor capacitances too, but why would the base-emitter capacitance increase so much when the collector voltage is low?

Also, the base-collector capacitance would pull the base down and delay the transistor turn ON, through the Miller effect, when the dv/dt on the collector is high but it seems that the dv/dt increases with the collector voltage, not the other way around.

Yes, but the delay in the turn-on itself is what accounts for the moving waveform as the collector voltage is varied. The time between the trigger pulse and the transistor "waking up" seems to be related to the applied voltage in a straightforward manner.

Maybe the +V2 is sagging when it is low, but shouldn't that be visible on the yellow Ch2 trace which is referenced to +V2 when capacitively coupled to pin 4/8 ?

I dunno in Itsu's video, but I think it can be seen in your trace image above, where there is a little voltage rise on the yellow trace at the same time the red trace makes the abrupt current spike. In Itsu's video he's using the trigger transformer, right? So that fast blip of voltage rise right there might not make it onto his yellow trace.

I agree with Сергей that researching the cause of these delays when the +V2 voltage is low, is not essential to generating the nanosecond pulses which will be generated at higher +V2 voltages anyway.


All knowledge is interesting and many times, the most interesting stuff is found in branches off the main line. Don't sweat it, go where the "pulsations" lead you.
I just got confirmation that my old DP-101 nano pulse generator has been packed up, along with some other of my kit, and is being sent over to me. Should be here in a week or ten days... by which time I'm sure you will have all your issues sorted and will be making even faster risetime pulses than that unit (~3-7 ns). Btw, I just checked EBay and these DP-101 and DP-100A units are available cheap...

[itsu]

to Itsu

What's going on with your Nano-Pulser Itsu ?

I think your ferrite rings are ok, transistor ok, driver ok, oscillograph ok. Maybe is time for you to start new blank page

If you can't get proper Nano-Pulse that it mean your 1n5408 diode is not good for that. Try to find old Diffusion Rectifier Diodes (bunch of them) and to make test every single example.

Сергей В.

Inbetween the lines (videos's), i also made some experiments with severall diodes i had in my junkbox
But none is showing any extraordinary behaviour
The best result was with the 1N5408 showing 300 V but with 150 collector/drain voltage.

So i just simply cannot replicate this nano-pulse behaviour yet with the stuff i got.
But i am sure with the help of verpies i will get there.

Regards Itsu

[verpies]

Yes, but the delay in the turn-on itself is what accounts for the moving waveform as the collector voltage is varied.

But the internal transistor capacitance cannot explain the transistor 'waking up", after the base-emitter current has fallen down to zero, yet this is clearly seen on Itsu's video.  The U3 is not providing any current into the base anymore, yet the transistor "wakes up" much later despite the lack of any base current. 
WTF!? - a capacitor is not a delay line!

The time between the trigger pulse and the transistor "waking up" seems to be related to the applied voltage in a straightforward manner.

Yes it does, but how can the transistor "remember" that a pulse on the base has started (and ended!) in the past.
It would be a different story if the base pulse still was happening when the transistor "wakes" up ...but the pulse is long gone by that time!

Also, the base-emitter voltage and current do not depend on +V2.
They only depend on +V1 and the resistors between the UCC52711 driver and the base of the BJT.

[TinselKoala]

Ah... yes, I see what you mean now. You're right, I hadn't considered that the drive pulse was actually off before the transistor responded. And the inter-gate switching delay of the logic gates is too small to account for the delay, and that wouldn't be variable like that either, I shouldn't think. Well, it would be nice to see the trigger pulse on one channel and the signal right at the base lead of the transistor as close to the transistor as possible, to see if what the yellow trace is telling you is really what the base is seeing in the first place.

[Black_Bird]

@itsu
My experiments also show 300V pulse on 1N5408 with 150v power supply. I had to reduce the number of turns for both primary and secondary to 4 turns. I could increase the amplitude a little bit by paralleling two 1N5408s, to 330V. I also made a PSPICE linear simulation (no saturation) and it shows that the pulse will still occur, even without transformer saturation, but simulation shows it should have an amplitude of about 650V and that it depends on the current that flows on the secondary inductance and on the capacitor value, as expected. In my case, I assembled the diode directly at the coax input, but I'm using a wire to get to the pulse transformer. Probably this is what is disturbing the voltage. I'll try to reduce it and see what happens.
P.S: I moved the pulse transformer and capacitor to the coaxial cable input and the wires now go to the MOSFET drain and to the power supply. It actually got worse.