Kapanadze Cousin - DALLY FREE ENERGY

[gyulasun]

Hi Nick,

It is unfortunate that the new 24V PS does not provide the specified 10A current and also dropping
below 24V for large loads. Then using the high power rated resistor load values I suggested yesterday
(from 2.5 Ohm to say 3 Ohm) will only reveal what you already know... but if you have not tested your
new PS with resistor loads, it would be worth doing it to learn how it exactly behaves in the 6A to 10A load current range.
Perhaps you could consider to send it back to the ebay seller and get money back, if it is not too late?

Regarding your two or more chokes in series with the center tap of the Mazilli sounds good but do you know
how many uH or mH their resulting inductance is? (especially under the some Amper current draw)
My series choke coil suggestion of at least some hundred mH came from your info
on the overcurrent protection circuit kick off in the 24V power supply, a high value choke would resist
the intial high current draw the Mazilli may demand at the very start up moment,  that is all.
Or the series resistor test advice was also meant to prevent the initial higher than 10A current draw that may take place.

Suddenly I cannot recall whether your FETs still overheat at 12V battery or not?, sorry.  If you meant in your
above reply they overheat with the 24V supply (and not with the 12V) then the 24V for the Mazilli oscillator
is already too high.  I built oscillators in the mW range only and found that they sensitive to power supply levels,
some of them are willing to run within a certain supply voltage range (yes, too low voltage may also kill oscillations).
Sorry that no hands on experience with Mazilli type power oscillators...
what you could do is to test other diodes in place of the cross-over diodes i.e. instead of the UF306 even though
it is also an ultrafast type (has a reverse recover time of 75 nanosec,
from  http://pdf.datasheetcatalog.com/datasheet_pdf/transys-electronics-limited/UF300_to_UF308.pdf )

It may also help if you check the gate-source voltage waveforms of the FETs in the Mazilli oscillator with the
scope to see how the gates are controlled in reality, whether one of them really switches off for a half period
while the other FET is ON etc. this at both the 12V and at 24V supply voltages and compare.

Gyula

[T-1000]

But, still too much heating of the fets. No other components heat up, only the fets which become untouchable in about 15 seconds running time, even when running a single 100w bulb, and more so on higher loads.

Try to attach fast Shotky diode to each output of FETs in series to the coil and see if heat goes away. I suspect the reverse currents are heating internal diodes of FETs there. The diodes like in http://www.st.com/web/en/resource/technical/document/datasheet/CD00110358.pdf should be OK.

Cheers!

[Tomtech29]

Hi.
NickZ
-Now you have a high voltage to the gates of Doda 18V zener need to change. (and any ultra-fast diodes) and the system will work.
or still try

[NickZ]

  TK and All:
  The zeners are:  CENTRAL ZC535B. 18v, 5w.
  The cross-over diodes are UF 306, and I've also used the IN4007, previously.  Both are 1000v rated, I believe.
  Normally I have heating issues, which is almost always, when running 300+ watts worth of bulbs.
  The IRFP260N is rated at 280w, but will heat up even on a 100w load. The Mazilli is known for that kind of over-heating issues, but it should do better, than not being able to be used for over a couple of minutes running, even on 12v, with a 100w load.
The volts don't seam to matter too much, one way or the other, but the amps do matter. It can even run on 12v, 2 amps, and still partially light a couple of 50w bulbs, with normal heating temps.
  I was hoping that the 18v zeners, and 24v PS would help to control the heating issue, but that doesn't seam to be the case, at least not as I have it set up now.
  As I hate to hear heat-sink fans whizzing away, I'd rather have a lower amp output, but passive system cooling, without fans.
 
   The grenade coils, add higher voltage output to the circuit, but at the expense of use-able amps.
  In any case, I do still need to get the right 0.47uf WIMA 2000v caps, and the 1.5uf 1000v WIMA caps. Also the right Kacher transistor, (the 2sc5200), and any other needed part to make it work, like the 70v, 200w mosfets.

   I'll test the fets on the scope, again, and see what they look like, now. 
I'm almost sure that although the fets seam to be ok, they may not be, as mayor overheating is also a sign of only a single fet working right.
  The next fets that I'll need to order some of, are the 70v 200amp ones, that I also had mentioned some posts ago, (I forget their value numbers), right now.
 
  Thanks for the help, guys.

[Dog-One]

  The next fets that I'll need to order some of, are the 70v 200amp ones, ...

You may want to look at the IRFB3077's.  They will certainly sink some amps, but the circuit has to be right and has to redirect any BEMF away.  I have yet to make these overheat but if they get spiked, they will switch no more.