Kapanadze Cousin - DALLY FREE ENERGY

[verpies]

So you are elevating the trigger reference to +150 volts because of the need to have the other scope probe references also at +150?

Yes, the current sensing resistor (CSR) must be on the high side of the power supply because Itsu is using N-Channel transistors.
If the CSR was below the emitter or source, then the transistor would operate in emitter follower mode or source follower mode (not what we want). Also a CSR on the low side could not sense the current in the flyback diode.
It is useful to know exactly when the power switch is supposed to start conducting, by observing the base/gate signal path, in order to tune the charge going into the DSR Diode.

I think it's better to use the trigger transformer scheme.

So do I.

Sorry, I don't want to confuse this excellent tech discussion, I'm trying to follow along as best as I can.

Don't worry about it. I appreciate your input and I'm open to constructive criticism.

[TinselKoala]

OK, thanks.... I got it now. Too bad differential voltage probes are so expensive. I would find one very handy myself.
It would seem also that you are working in a region where physical layout is going to be important too. I'm learning a lot from following along, so thanks again for answering my occasional question. Carry on!

[itsu]

I hope the simple pF capacitor scheme works with your scope, however the scheme with the trigger isolation transformer (TT) is better and safer.

Ok, i used both technics, but both mutilate the nice square pin 8 signal.
Also "the horizontal moving across the display" of the current trace is still there.

Mind you that my pins 8 and 9 are still joined together as in the original design in post #484 on page 33 as are pins 10,11 and 12 and pins 2 and 3.

I will try to "upgrade" to this next version and redo the testing.

Let me know if any improvement is to be expected when using a better 1:1 transformer.

Video: http://www.youtube.com/watch?v=C_RgII6sXU8&feature=youtu.be

Regards Itsu

[verpies]

Ok, i used both technics, but both mutilate the nice square pin 8 signal.

I did not expect to see a nice rectangular signal on the yellow channel (Ch2) of your scope !!!
I am happy with what you have, because the yellow channel nicely illustrates when the power switch (BJT or MOSFET) is supposed to turn ON and OFF.

The pulse shape should become more rectangular if you place a 10k resistor in parallel with the secondary winding of the isolation transformer.  We could do even more work to eliminate the distortion by better impedance matching or a better transformer (faster core), but it would be a waste of time because we are not trying to reconstruct a perfect rectangular pulse appearing at pin 8.

In the capacitive coupling method, you could decrease the pF capacitor even more, in order to minimize the capacitive load presented at the output of the NOR gate (at pin 4 of U3).  You can keep decreasing the pF coupling capacitor (the smaller it is, the less work for pin 4) and increase to 10k resistor in series with it, as long as the rising/falling edges are sharp and clearly visible on the scope's Ch2 (yellow) and if these edges can be used to trigger the scope.  It is sufficient information even if Ch2 displays only two needles (Dirac Pulses) coinciding with the rising and falling edges of the rectangular pulses appearing at pin 4 (pin 4 of U3)

Also "the horizontal moving across the display" of the current trace is still there.

Indeed, when you were triggering on the capacitively coupled signal from pin 8 (or pin 4) that effect was clearly visible. 
I was ignoring it up till now because the traces were not clear, but now I have to think more about it.  Maybe Mr. Koala or Poynt99 could help too...

Mind you that my pins 8 and 9 are still joined together as in the original design in post #484 on page 33 as are pins 10,11 and 12 and pins 2 and 3.
I will try to "upgrade" to this next version and redo the testing.

Yes,  please break the connection at least between pin 8 and 9 and ground the pin 9, so the pin 4 has less work to do.
...or if you have the energy, redo U3 wiring like on the attached schematic.

[verpies]

This is a sample how the waveform on Ch2 helps me read the current waveform on the yellow Ch2.