Re: [TCML] flyback primary wireing

["DC Cox" <resonance@xxxxxxxxxxxx>]

I use 2 turns on the feedback winding and 10 turns on the primary winding
--- Litz wire for the HF.

My flybacks are larger than normal with 4,200 turns instead of the usual
2,800 turns (#42 AWG).  I based the design off the large flyback used in the
1969 Zenith color TV, only increased the sec turns from 3,900 to 4,200 for
slightly higher output.

If you run this circuit with the @2N3055 you will keep blowing transistors.
I use a similar circuit but a much more robust 450 VDC 30 Amp RMS continuous
transistor.  At a low $6.00 works almost indefinitely with a large heatsink
and a 60 CFM blower.  I run 16.2 VDC at 2.2 Amps with my flybacks.  I have
the circuit if you wish to contact me off-list I wire fire it off to you.
Avoid using MOSFETs --- they are so efficient they provide excessive current
in the flyback output which will burn a hole in your stem --- ask me how I
know this!  That's why the Info Unltd MOSFET units will destroy your globe
in short order.

Dr. Resonance

On Fri, Aug 15, 2008 at 10:01 PM, Scott Bogard <teslas-intern@xxxxxxxxxxx>wrote:

>
> Hey all,
>     A quick and quasi off-topic question, how does one determine the
> best number of primary (and feedback) turns to use on a simple single
> transistor flyback driver (like this one
> http://bogard.110mb.com/Plasmaglobe.htm
> ?)  I seem to be getting the most power using the original 2 turn
> primary, but most sources say 5 or more turns is best.  Is it simply a
> matter of desired impedance or is there more to it (like the transistors
> internal resistance, or the ratio of the two other resistors.)  Thanks,
> feel free to respond off list, as this is quasi-off topic.
>
> Scott Bogard.
>
>
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