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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: LTSpice model for a SiC MOSFET
Date: Wed, 21 May 2025 12:05:28 +0100
Organization: Poppy Records
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Bill Sloman <bill.sloman@ieee.org> wrote:

> On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
> > Bill Sloman <bill.sloman@ieee.org> wrote:
> > 
> > [...]
> >>> Capacitive divider using a spare core in the
> >>> mains supply lead as one plate of the capacitor?  (Depending on supply
> >>> frequency and required output current.)
> >>
> >> I can't see how that could work.
> > 
> > If you used a three-core mains lead with one of the cores connected to
> > Neutral at the plug, one to Live at the plug and one floating, the
> > floating lead would take up a potential somewhere between the other two,
> > the stray capacitances between the leads acting as a capacitive divider.
> > 
> > The Live and Neutral leads are left unconnected at the equipment end and
> > the floating lead is connected to a rectifier system which takes it's
> > earth reference from the equipment being supplied.  It would be
> > approximately a constant-current supply, so a capacitor and zener diode
> > would be sufficient to stabilise it at the required low voltage.
> > 
> > The mains lead is acting as a high voltage capacitor but is a lot
> > cheaper and more reliable.
> > 
> > If you need a solid earth on the output, use a four-core cable.
> 
> That's a lot of words but doesn't describe anything that takes a small
> direct current at high voltage and turns it into larger current at a low
> voltage.

The original post didn't say that it was a direct current source.  My
comment "Depending on supply frequency and required output current."
would have given you a clue that I was assuming an A.C. source.

-- 
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk