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Re: CGA Monitor Flyback ???
Hi Grayson,
> Original Poster: "Grayson B Dietrich" <electrofire-at-juno-dot-com>
>
> Hello, Nick, and all
>
> On Fri, 25 Feb 2000 16:38:44 -0700 Tesla List <tesla-at-pupman-dot-com> writes:
> > Original Poster: "Megavolt Nick"
> > <tesla-at-fieldfamily.prontoserve.co.uk>
>
> <snip>
> > Commercial plasma globes use a cockroft walton multiplier to create
> > the HV.
>
> They do? I thought that a plasma globe needed high frequency AC to
> operate. A voltage multiplier will give pulsed DC... and are you
> referring to -very- large globes? I've had a chance to see the schematics
> for some commercial supplies, as well as the actual supply from an 8"
> unit, and none used voltage multipliers, and had no diode as in TV usage.
A commercial plasma globe system I repaired a few years ago used
a pushpull circuit driving a ferrite cored transformer and the power
supply transformer (two in parallel actually) was preceded by a triac
dimmer type circuit to give a range of output powers. I was amazed
at the amount of oomph needed to drive the globe which was
approaching 3 feet in diameter and exhibited a rather high terminal
capacitance. Failure of the driving transistors was caused by a
cracked ferrite core, probably through overheating (it was a self-
driven oscillator) causing the core to expand and try and push its
clamping screws apart.
Regards,
Malcolm
<snip>