I need an help to redraw a circuit,please...

[Cyrano]

Hi People...
I need some help to try to arrange the oscillator circuit on the left of the picture, to drive the coils setup showed on the right with three IRF840.Thanks for any help.

[Cyrano]

I'm sorry, but i'm unable to attach the image.You can see it here:
http://img121.imageshack.us/i/mosfet.gif/

[dyarker]

Shoudn't the 50K bias pot go to lower end of drive coil? Right now the feedback coil and FET gate only "see" filtered DC from supply.

What is the diode in series with drive coil for?

Oscillators on purpose are hard. Oscillators by accident when trying to make an amplifier are easy.

Cheers,

[dyarker]

RE: Posting images.

Did you try putting link in your second post inside image tags of first post?

In Edit image tags look like [ i m g ] link [ / i m g ] (without the spaces)

Cheers,

[Cyrano]

The biasing pot is part of voltage divider to get the Fet's in range.

To allow disconnection of the internal FET diode, a separate diode can be added pointing to the drain (coil-diode-drain) This will unclamp the flyback emf on negative swings. The dotted diode is called the "parasitic" diode. It is inherent to the fabrication process of FET's wafers. It will clamp the free oscillation of your coil unless the disconnect diode is provided (coil-diode-FET).

[dyarker]

The biasing pot is part of voltage divider to get the Fet's in range.

No feedback, no oscillation!

The DC resistance of drive coil is very low and won't affect operation of bias pot if connection is moved. I don't know fer sur that moving bias pot lead will make the circuit operate. BUT I AM VERY SURE THE WAY IT IS DRAWN NOW, WILL not OSCILLATE. (unless drive and feedback coils are on same core, in which case it is still drawn wrong)

Cheers,

[Cyrano]

Yeah,drive and feedback coils are on same core,I forgot to mention.All the 4 coils + feedback are on the same core.I'm sorry...