Re: power supply questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Ed Phillips <evp-at-pacbell-dot-net> 

Tesla list wrote:
 >
 > Original poster: dhmccauley-at-spacecatlighting-dot-com
 >
 >  > Hello!
 >  >
 >  > I have two questions about changes I want to make to my power
 >  > supply:
 >  >
 >  > 1st: I only have one variac to controll the main HV transformer.
 >  > Currently I use it in standard configuration and additional
 >  > inductive ballast to limit the current. By means of that I
 >  > experience a lack of output voltage due to the voltage drop in
 >  > the ballast / variac. Can one use the variac to controll the
 >  > current ( in series ) WITHOUT using one to controll voltage?
 >  > Would that give a voltage gain?
 >
 > You can use a variac as a variable inductor.  However, inductance will vary
 > from variac to variac and so will the current ballasting.

	Unless the core is gapped it will act more like a variable saturation
device than in inductor. As the number of turns is reduced the flux
density in the core will increase to the point where severe saturation
will occur.  "A lot of guys are doing it" so I guess that means it
works, but my guess is they are all way, way into core saturation.

Ed