Kapanadze Cousin - DALLY FREE ENERGY

[Hoppy]

Evening Hoppy.

How do you think a Zenner would stand up to crowbaring for the Ismael device? If you were able to bring up the voltage to just around the threshold of reverse it would conduct for a short period of time before going back to blocking as the sine wave decreased. Just a thought

Cheers Grum.

Evening Grum,

The problem with a zener is its dynamic resistance is far too high (according to Aviso), typically 10-15R, which is why Aviso is using paralleled IGBT's for extremely low drain / source resistance.

[NickZ]

    Hoppy: 
   Thanks again.  Back to back diodes as you say, is one thing. Which I understand.
But front to front, (or facing diodes), could be bucking diodes, and not protecting, at all, and may be doing something completely different? Especially is they aren't zener types. 
   Anyway just thinking out loud.

[verpies]

Back to back diodes as you say, is one thing. Which I understand.
But front to front, (or facing diodes), could be bucking diodes, and not protecting,

Series back-to-back, front-to-front, face-to-face and bucking diodes means the same thing.
Series back-to-front and front-to-back means something else.

[verpies]

Back-to-back diodes don't conduct in either direction until their reverse breakdown voltage is exceeded.
Such connection of diodes is bidirectionally symmetric and behaves just like a varistor, but usually faster and at lower voltages.

Single diodes or back-to-front diodes conduct in one direction and when their collective reverse breakdown voltage is exceeded they also conduct in the other direction. 

[TinselKoala]

Why?  The TL494 already has complementary outputs.

Yes, and it was very frustrating to not be able to use them. I wanted more symmetry and more current than each complementary output could supply, so I fed one output to the 2n7000s to split that signal and invert one of them, then on to the bipolar H bridge. I'm operating the 494 well above its rated frequency range, and I think that accounts for the asymmetry of the chip's own outputs.

Does that bridge have a better performance than integrated MOSFET gate driver (e.g.: UCC27511) ?

Probably not "technically" but it's a lot more robust, and easier to change parts. Instead of replacing the whole driver chip I can just replace the failed transistor, etc. So in that sense the performance is better.... But the "hot setup", after all the problems are sorted, would do away with the 494 and the bipolar bridge, and use a CMOS pickup to drive the gate driver chips directly.

Cool.  Is that antenna difficult to tune ?

Not at all. I didn't label it in the photo but it's the chip and LEDs at the bottom right of the osc board. The antenna is about 3 inches of bare wire, just plugged into one of the gate inputs. The output of that gate is run thru a couple other gates in the same chip to drive the LED and to clean it up for the alternate drive into the splitter/inverter stage. Sometimes you need to touch the antenna with a finger to get the thing to start.

...and what are the dimensions of the secondary winding?

I think I used around 700 turns of #33 Kynar-insulated wire-wrap wire on a short fat Bakelite form, and two chrome baby-moon hubcaps for the top capacity.