Kapanadze Cousin - DALLY FREE ENERGY

[Hoppy]

  As the new Zener diode delivery has not made it to my place, yet. I can't test to see if the heating of the Fets will be reduced by installing them, instead of the 12v 0.5 watt zeners that I'm currently using. The resistors that I'm using are the 10 OHM, that are recommended for the Mazilli crt that I posted previously. That circuit is what I built, as well. It is a fairly simple circuit, but several people have complaints about heating issues, also.

 

Nick,

Where are the 10R resistors placed in your circuit? I don't recall seeing any Mazilli circuit posted that had 10R resistors shown.

[NickZ]

  Hoppy:
  Thanks for your concern, I appreciate it.
  The resistors that I'm currently using are the 10K OHM ones, not 10ohm, nor, 10R.
As are shown in the induction heater circuit shown below.
  I would think that using the bigger heftier diodes, zeners, resistors, and caps that Akula uses, makes for a much better circuit. Although he does have three heat-sinks and fans, on all his fets and transistors. For a reason... and those three fans also consume some juice from the circuit.

  EDIT:  After looking at the diagram, I may not have it right, as I have connected both the zener diodes, AND 10k resistors to the same blue colored (negative), which also goes to the battery negative rail. Is this wrong, or not?  As I can't tell from the circuit diagram.
   Also pictured below is one of Geo's diagrams, with diodes.

[TinselKoala]

Well, if people won't listen to my advice, which I have given about these circuits several times before, maybe when itsu and void are telling you the same things (use multiple poly film caps of the same value in parallel to make up the total cap value needed, use short heavy direct symmetrical wiring paths for all the tank circuitry (mosfet drain, capacitor bank, coil), apply ample gate drive voltage, clean signal to gate, have the Gate circuitry tight and symmetrical) folks will take _their_ advice and your heating problems will go away. I'm sure you have all seen my videos where I run essentially the same circuit, using the same P260 mosfets, for long times at high power without any overheating problems in the circuit. The loads I run can overheat since they are getting so much power throughput, but the driver circuit itself does not run excessively hot, if I use the proper capacitors. The Sprague orange drops are very good and I recommend them, however I have been able to fail a couple of them from overvolting, usually in the receiver part of the complete apparatus. Select poly film caps that are voltage rated at 10 to 20 times your supply voltage! Build up your capacitance value by using several lower-value, equal, caps in parallel.
I like to use 10 caps of 1/10 the desired final capacitance value, just because it is easy to do the math. For example if you need 100 nF, use 10 ea. 10 nF in parallel, all the same, all with at least 250 V rating.
Part of the mosfet-heating problem is reflected power from the tank circuit. This is the same problem that CBers and Hams encounter with antenna matching. If your SWR is high you will have lots of power reflected back into the output transistors and they will overheat. In these present circuits "Low SWR" translates into symmetrical output wiring, few interconnects, short and heavy conductors for the tank itself.

[Hoppy]

  Hoppy:
  Thanks for your concern, I appreciate it.
  The resistors that I'm currently using are the 10K OHM ones, not 10ohm, nor, 10R.
As are shown in the induction heater circuit shown below.
  I would think that using the bigger heftier diodes, zeners, resistors, and caps that Akula uses, makes for a much better circuit. Although he does have three heat-sinks and fans, on all his fets and transistors. For a reason... and those three fans also consume some juice from the circuit.

Nick,

The small 0.6W resistors are fine for the 10K. Make sure that the 470R resistors are at least 3W as shown. Enough has been said about the zeners! Your mosfets are fine. Most importantly, get a higher capacity batteries in good condition as you will still be pulling big amps at 24V!

Edit: Your zeners and 10K resistors are connected correctly. Please note that the zeners are there to help protect the mosfet gates from overvoltage. You may still experience mosfet overheating if you do not follow TK's advice above.

[NickZ]

  Hoppy:
  Ok thanks for checking it out for me, and confirming that I have it right, as shown.

   This Mazilli circuit is basically USELESS, as is. It can only be run for a few seconds at a time, without overheating. That's why I don't recommend it to anyone. I tried it with two 12volt batteries in series, at 24 volts, and blew both of the IRFN260P fets, instantly. So, even though my batteries are old, this circuit could not handle that current, from basically dead batteries.  It doesn't matter if I just have a 25 watt bulb connected, or 7 100 watt bulbs, the overheating is present at any load.

  TinselKoala:
   I don't know if you are talking about my circuit, or in general. But, I am using short tight connections, soldered, and with several 400+ voltage poly caps in parallel, which are not heating up a bit.
   Please connect up a 700 hundred watt load to your IRF 260 fet circuit, and leave the circuit running for an hour, as a test to see that there is no overheating.
I will believe it then.