Kapanadze Cousin - DALLY FREE ENERGY

[NickZ]

  Isn't that what the choke is supposed to do?
  When using two chokes I actually get slightly higher voltage and bulb brightness.
  I did buy some 12v zeners but have not tried them yet, until I can get more fets.  However, they may not be the right ones, either.
  Package says: # IN4742A   12v,  21mA, maximum power dissipation 1.0 W 
  So, are these any good for this? They were the only one that I could get from the Shack.    However,  I don't see Igor using them so far.

  What I really don't understand is why I'm only getting 35v output, when Itsu is getting 600+ volts from his yoke, and Geo was getting 120 to 160 volts on his yoke circuit.

[Hoppy]

  Isn't that what the choke is supposed to do?
  When using two chokes I actually get slightly higher voltage and bulb brightness.
  I did buy some 12v zeners but have not tried them yet, until I can get more fets.  However, they may not be the right ones, either.
  Package says: # IN4742A   12v,  21mA, maximum power dissipation 1.0 W 
  So, are these any good for this? They were the only one that I could get from the Shack.    However,  I don't see Igor using them so far.

  What I really don't understand is why I'm only getting 35v output, when Itsu is getting 600+ volts from his yoke, and Geo was getting 120 to 160 volts on his yoke circuit.

Yes, the choke does limit peak current but does your choke have sufficient inductance to limit the peak current to a safe value for the mosfet you are using? Do you have an LC meter to measure the inductance of your choke?

As I've said before, get yourself some 15V/5W rated zeners. Zeners with a 1W rating are from my experience, having built several working Mizzilli's, not suitable for this application.

The impedance of the LC network limits current, so with the small mosfets you have had some success with, their RDS (resistance drain to source) is quite high at around 0.5R, so as impedance is the total reactance plus resistance, this is high enough to limit your peak current to a much lower value than if you were using bigger mosfets with a much lower RDS. This is part reason for your low output voltage.

[NickZ]

  Ok, well I'll see what I can do to obtain the bigger 260N fets, as well as the 5 watt zeners.
  Anyway, here are a couple of pics of the transistor version.
  It may also be that not all of my yokes work the same, and I may have to rewind one to test the difference that different windings can make.

[SeaMonkey]

(c)  Isn't bad at all to use a current limitation supply bellow maximum current rated for FETs.

Sometime these royer or mazzily configuration stop oscillating especially when LC tank is low Q, or when  L is hardly loaded as the primary of a transformer. When such circuitry stop oscillating both fets remain in conduction, and then without a current limitation, bumm!

Excellent!  This is perhaps the best solution of all,
at least initially, until other "bugs" are worked out.
Clearly the voice of experience speaking. This
precaution is standard in the World of R&D by the
way.

  It is also true that if the fets won't oscillate, for whatever reason, they burn up in a blink of an eye.

Only if you don't limit the supply current. 

Aye, 'tis very true.  Without reasonable current
limiting the MosFet can be converted to a "short
circuit" incredibly fast!  Learning how to limit the
current to avoid such catastrophes is a most
valuable skill.

[Grumage]

  Isn't that what the choke is supposed to do?
  When using two chokes I actually get slightly higher voltage and bulb brightness.
  I did buy some 12v zeners but have not tried them yet, until I can get more fets.  However, they may not be the right ones, either.
  Package says: # IN4742A   12v,  21mA, maximum power dissipation 1.0 W 
  So, are these any good for this? They were the only one that I could get from the Shack.    However,  I don't see Igor using them so far.

  What I really don't understand is why I'm only getting 35v output, when Itsu is getting 600+ volts from his yoke, and Geo was getting 120 to 160 volts on his yoke circuit.

Dear Nick.

Are you measuring your volts with a DVM/Voltmeter ? Because if you are you will not be seeing the true voltage due to the high frequency. You could try making a FWBR from 4 X 1N4148 and see what you get. Also don't forget that Itsu and I were quoting P/P voltages read off the scope ( I know I was!!) this value should then be multiplied by 0.707 for a rough RMS value that your DVM does automatically!!

As another test try using the 12 V secondary of a "biggish" transformer as your in line choke, you should see a "Boost" to the voltage you have now!!
But the great thing is you have not fried the transistors !!

Cheers Grum.