[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: Re: hvguy-dot-com new flyback driver
Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rob-at-pythonemproject-dot-com>
With MosFETS, you use a low value resistor to ground, like 10 or 20 ohms.
That quickly gets the charge out of the gate, and makes it harder for the
Cgd to pull on the gate. My experience with MosFET driven flybacks was that
they produced lower voltage but higher current on the secondary. Thus the
arcs were shorter but more intense. I don't think I ever tried the L-C
circuit on a FET.
This weekend I am going to try to make a PSpice schematic of my old npn
circuit, then I can email it to whoever wants it. But I can only estimate
the values of the L-C circuit on the base. Rob.
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>Sent: Thu, 02 May 2002 20:17:18
>Original poster: "by way of Terry Fritz
>In a message dated 5/1/02 8:25:19 PM Eastern
>Daylight Time, tesla-at-pupman-dot-com
><< When I was a kid, I perfected a flyback circuit
>that worked with a single
> 2N3055. The key was putting an inductor (couple
>of mH?) directly from base
> to emitter to suck the charge out of the base
>during turn off. I used 20
> turns of secondary on the bottom rung of the
>flyback, and 2 turns of
> tickler coil connected via a cap to the base.
>This was an oscillator. You
> start the oscillation by hitting a button which
>spikes the base line, then
> its free running. I used to be able to flash over
>and incinerate the
> biggest flybacks from the 70's, with about 30V
>Vcc. This circuit was very
> efficient since the L-C high pass character of the
>tickler circuit pulsed
> the transistor with a very short width. Rob.
> ps. I'd love to build one of these again, but
>those old flybacks are
> no-where to be found except in landfills
>Hmmm, sounds interesting.So an inductor would help
>out?What about using an
>inductor with a mosfet?
>Isnt it sad that those NICE flybacks are all under
>dirt?I REALLY wish I had
>more. I have an ok one but it has many secondary
>outputs although its a good
>3in diam by 1in disk.Maybe we ought to "mine" these
>kidding!Any ideas where to get these?Surely they
>are stockpiled somewhere.