Re: EMI Filters

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Karl Lindheimer <karl@xxxxxxxxxxxxxxx>

Hi Paul,

If I understand correctly, you state that the EMI filter is between the 
wall outlet and the variac?  If that is the case, the filter will only 
reduce any back EMI from reaching the wall outlet and the rest of the 
connected house wiring on the same circuit.  The variac and meter are still 
exposed to the EMI from the coil.  My flyback transformer experiments also 
created huge RF/EMI necessitating that I disconnect any valuable/sensitive 
equipment from the AC line.  I ended up building a robust simple power 
supply to spare my lab grade bench supply.

Karl

On May 5, 2005, at 1:20 PM, Tesla list wrote:

> I have a 20A EMI filter wired in reverse between the wall outlet and my 
> variac. I have a volt meter attached to the variac outlet.
>
> I was driving one of my ignition coils with a 600 watt dimmer in series 
> with a 2mF cap. As I powered up the variac, I could read the voltage 
> increasing on the volt meter all the way up to 120V. When I turned up the 
> dimmer, the voltage indication on the volt meter went haywire when the 
> coil began sparking. If I drew the ground away from the HV output, the 
> volt meter would stabilize as soon as the sparks stopped.
>
> What have I missed here? This isn't normal, is it??!! Could the EMI filter 
> be bad?
> Paul
> Think Positive