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Re: DC Tesla Coil
From: Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: bert.hickman-at-aquila-dot-com
Sent: Monday, January 05, 1998 1:54 AM
To: Tesla List
Subject: Re: DC Tesla Coil
Tesla List wrote:
>
> From: Alfred C. Erpel[SMTP:aerpel-at-op-dot-net]
> Sent: Sunday, January 04, 1998 7:25 PM
> To: Tesla List
> Subject: Re: DC Tesla Coil
>
> Greg and All,
>
> AE>> To get DC into the tank
> AE>> capacitor, is it as simple as feeding rectified AC into your
> transformer?
>
> GL> ??!!?? Only the AC component of the ripple would make it
> GL> through, assuming the core wasn't saturated...
> GL> The DC component would simply treat the transformer as
> GL> a space heater. Rectification must occur after the xfmr.
> >
> >
> >-GL
>
> Your the second person who questioned this. I will clarify what I mean.
>
> WARNING, PATHETIC ASCII ART FOLLOWS:
>
> the symbol > below, denotes diode pointing in + direction
>
> ----------------o
> / \
> / \
> > >
> / \
> 120 AC in o o-----------0||0--------tank circuit
> |\ / 0||0
> | > > 0||0
> | \ / 0||0
> | \ / 0||0 neon sign transformer
> ----------------o 0||0 secodary
> | 0||0
> | 0||0
> | 0||0
> o---------------------0||0--------tank circuit
>
> Wouldn't the wave form below, put out by the bridge above, be just fine
> to as an input into a NST primary?
>
> |
> | --- --- ---
> | / \ / \ / \
> | / \ / \ /
> | / \ / \ /
> |/ \/ \/
> ----------------------------------------
> |
> |
> |
> |
> |
>
> Regards,
> Alfred Erpel
Alfred,
A transformer will not transfer any DC portion of a waveform from the
primary to the secondary. No matter what kind of input you apply, a
transformer's output will always "average" to 0 volts DC - the "area" of
the waveform that's above 0 volts will be matched by an equivalent
"area" below 0 volts so that the overall average is always 0 volts. Any
rectification MUST be done on the secondary side. If you attempt to
apply full-wave rectified DC to the input side of the transformer, the
effective DC portion of the waveform will merely heat up the primary
winding, and possibly saturate the core. Assuming you don't saturate the
core, the output will look much like the AC component of the input, with
equal "areas" of the waveform above and below the 0 Volt line - but no
DC.
-- Bert --