Kapanadze Cousin - DALLY FREE ENERGY

[AlienGrey]

HI MATE WHERE CAN I BUY THIS PCB.

WHY WOULD YOU WANT TO DO THAT ?

for a start it has no way of syncing the EHT section with the with the card (no output) and for another, you have no way of feeding the output spikes from the drain back into the system, and for another, you will have to make the card for yourself.

No thanks!

[itsu]

Nick,

Yes, I can verifiy that I can do the same thing, and show the same type of controlled square wave, as you just posted.
HOWEVER,  and it's a BIG However,  the rest of the system does not work as it should. Or at least as I was hoping. And as you have seen, neither does yours. Especially when connecting it all up to the rest of the whole set up.

So you have right now the same circuit as put up in my last post, is that including the 1K output resistors? (i thought you lowered them as verpies pointed that out)
The floating output signals should be fixed.

Do not connect up the rest of the system, first try to get a stable TL494 circuit to work with.

Does it still show dropping outputs and/or oscillations when turning the pots?
Do you have a 0.1uF ceramic cap right across the TL494 plus / minus leads (pins 7 and 12)?

What are these red circled resistors values's?   i see 1KOhm, whats the other and how are they connected up (1K's to ground, other to TC4420?).


Itsu

[verpies]

Pin 3 is floating, but when connecting it to pins 2, 13,14, 15, it shuts down the output signals.

Of course because on that schematic diagram, pins 2&15 are connected to pin 14 and on my schematic they are not.

The floating seems to come from the 1K resistors, they are to high, probably lower value resistors will fix this.

Yes, if taking the output signals from pins 9 and 10 then these pins must be grounded through smaller resistors.
I recommend these resistors to be around R=V_CC*10, where V_CC is the voltage between pin 7 and pins 8&11.

[verpies]

I suspected that on your previous video, that the reason you kept the 45% or so duty cycle, steady there, NOT turning it too much. Was due to the same reason. And perhaps other guys have had the same issues, and may be part of why we get no where.

There is no mystery in the driving circuit, i.e. the TL494 + TC4420 or its duty cycle.
The mystery can be only with the components driven by it, especially with the large inductors/transmission lines.

What is wrong with my third try at this type of circuit? As ALL three TL494 that I've built all mess up the signal, big time,

The TL494 does not mess up the signal - it generates it.
Only the components down the signal path can mess it up.

and then burn all my fets, smoke my several in line chokes, etz...and, I don't have much hair on my head left to pull.
So...What to do? 

Do the due diligence.
Starting with scoping the V_GS vs. V_DS of your MOSFETs.  Several members and I gave already explained to you how to do it.

First do it with light bulbs connected to the final MOSFETs as a load and next, switch to the full "grenade" as a load .

P.S.
^{...and fix your scope by yourself - using TK's instructions preferably...}

[TinselKoala]

Of course because on that schematic diagram, pins 2&15 are connected to pin 14 and on my schematic they are not.
Yes, if taking the output signals from pins 9 and 10 then these pins must be grounded through smaller resistors.
I recommend these resistors to be around R=V_CC*10, where V_CC is the voltage between pin 7 and pins 8&11.

I doubt that the 1k pulldowns on the 494 emitter outputs are causing the problems. The 1k value works fine in my build of the verpies/stalker/TK(me) driver circuit.

Of course, this "assumes" that a stable voltage is being supplied to the collector inputs (pins 8 and 11).

The system can also work with grounded emitters (pins 9 and 10) and pullUPs on collectors with the signal to mosfet driver chips being taken from the collectors.