Re: MOT's (was UK Neon Sign Transformers)

To: tesla-at-pupman-dot-com
Subject: Re: MOT's (was UK Neon Sign Transformers)
From: "Steve Young" <youngs-at-konnections-dot-com> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Sat, 17 Oct 1998 20:05:11 -0600
Approved: terryf-at-verinet-dot-com


Mike and all,
----------
> >
> >Don't give up on MOTs!
> >Consider two MOTs with their grounded cores tied together.  Each MOT
drives
> >a half wave voltage doubler of opposite polarity.
> 
> Why not just put a single doubler across the two 'hot' outputs of the
> MOT's - presumably to enable the use of MW diodes/caps instead of
> higher-voltage parts ?
> >

The problem is the voltage rating of the oven caps which is only about 3 KV
DC (2100 AC x 1.4). Thus, instead of a single cap for the input stage of
the voltage doubler, you would need two in series, or 4 in series-parallel
to maintain the same capacity.  Likewise, the doubler output section cap
would need 4 in series, or 16 in series-parallel to maintain the same
capacity.  Caps in series need HV resistors across them to equalize the
voltage across the caps.  The bottom line is that two separate voltage
doublers requires less caps and associated resistor strings, if one uses
oven caps.  

If you make or buy higher voltage caps, then your scheme would be simpler,
assuming the oven diodes can stand the extra voltage.  

--Steve Young