RE: [TCML] RF Filters

["Lau, Gary" <Gary.Lau@xxxxxx>]

Aaah, OK.  While there is a resistor in the first schematic, it plays no role in the filtering; it's just there to bleed the caps in the filter so they can't hold a charge and zap someone.  It should be referred to as an L-C filter.  A Terry filter is an example of an R-C filter.

I would choose this filter over the second one, as it looks like it has several stages in it already.  More common EMI filters (like the one I use!) have fewer stages and presumably less attenuation.  Note in the chart how the attenuation drops off like a cliff below 100KHz!  I would doubt there's a lot to be gained by cascading two filters together.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Phillip Slawinski
> Sent: Tuesday, June 24, 2008 7:32 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] RF Filters
>
> http://www.delta.com.tw/product/cp/emi/general_two/download/pdf/DR.pdf
>
> One of the filters is 20DRGG5.  The other filter is much smaller, and does
> not have a schematic on it.
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130230886848
>
> On Tue, Jun 24, 2008 at 12:29 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
>
> > I've never seen an RC or RCL mains filter.  Running 20A through a resistor
> > would waste just too much power.  I guess I'd need to see an actual circuit
> > schematic to comment further.
> >
> > Realize too that the attenuation of common tank frequencies in most EMI
> > mains filters is actually pretty poor, if you read the specs.  They are
> > intended for higher frequencies.  I use an EMI filter, only because they're
> > cheap and small.  But I have little hope that it makes a real impact towards
> > reducing RF interference in the house.  To reduce the risk of _damage_ in
> > the house, I use 250V MOV's from Line and Neutral to green-wire ground.
> >
> > Regards, Gary Lau
> > MA, USA
> >
> > > -----Original Message-----
> > > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > > Behalf Of Phillip Slawinski
> > > Sent: Tuesday, June 24, 2008 11:28 AM
> > > To: Tesla Coil Mailing List
> > > Subject: Re: [TCML] RF Filters
> > >
> > > Mains filters.  One is a RCL the other filter appears to just be an RC
> > [much
> > > smaller size for the same amperage rating].
> > >
> > > On Tue, Jun 24, 2008 at 8:26 AM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> > >
> > > > That's something like asking if one can take more than one prescription
> > > > drug at a time.  You need to specify exactly what kind of filter and
> > what
> > > > the goal of the filtering is.
> > > >
> > > > Is this on the AC mains, or between the gap and the HV xfmr (i.e. a
> > Terry
> > > > filter), or are you talking about some other type of RF filter (that's
> > a
> > > > very general term).
> > > >
> > > > Gary Lau
> > > > MA, USA
> > > >
> > > > > -----Original Message-----
> > > > > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx]
> On
> > > > > Behalf Of Phillip Slawinski
> > > > > Sent: Monday, June 23, 2008 11:25 PM
> > > > > To: Tesla Coil Mailing List
> > > > > Subject: [TCML] RF Filters
> > > > >
> > > > > Is it okay to run RF filters in series?  Does it improve filtering /
> > or
> > > > does
> > > > > it hurt it?
> > > >
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