[Prev][Next][Index][Thread]

Re: Case ground.



Tesla List wrote:
> 
> >> Subject: Re: Case ground.
> >Subject: Re: Case ground.
> >> Subject: Re: Case ground.
> 
> Subscriber: knardell-at-mailhost.accesscom-dot-net Thu Jan 16 22:45:52 1997
> Date: Thu, 16 Jan 1997 00:35:34 -0600
> From: Kevin <knardell-at-mailhost.accesscom-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: Case ground.
> 
<SNIP>

> >> I again am having trouble with noise, I was showing my neighbor a new laser
> >> I just got and he said he could hear my coil running LOUD over his phone
> >> conversation. I have filters inline now, what else can I do? I put some
> >> chokes on the HV outputs of my neon and the coil stoped sparking. Why?? I
> >> also have a excelent rf ground, would this be a good time to pull the Neon
> >> case to the RF gound? My filter system is well grounded (The case) to the
> >> house ground as recomended by manufacturer. Any tips or hints, a faraday
> >> cage is out the question, I now have a coil, 2 lasers (Very big) and my
> >> other electronic junk in my play room, no room, money, or time to construct
> >> a cage.
> >>
> >> Anything I overlook?
> >>
> >> Thanks in advance!
> >>
> >>                                        Regards,
> >>                                             Kevin Nardelle
> >>
<SNIP>
 
> >
> >The 120V EMI filters you've added will only help reduce interference
> >that's being conducted back into your power mains through the wires.
> >They won't stop radiated high-frequency noise. It sounds like your
> >neighbor may be picking up radiated noise on his phone. Is his phone a
> >regular (hard-wired) or portable? Portable phones, being radio
> >tranceivers, are typically much more sensitive to radiated Tesla Coil
> >noise.
> >

> He has a regular hard wired type, cheapo.

> 
> >You can reduce noise radiation somewhat by making all of the high
> >voltage and primary/capacitor interconnection wiring as short as
> >possible, by minimizing the length of wire connecting your coil to
> >your RF ground, and using a solid RF ground (multiple groundrods). Tie
> >your transformer case to the RF ground as well. If you're still running
> >with the cap across the transformer, this may also increase the noise
> >you're radiating. Anywhere you've got a pair of balanced
> >current-carrying wires, like those going to the primary, run them close
> >together and in parallel to reduce their ability to act as individual
> >antennas.
> >
> I did just that, infact I am talking with a very nice person, and I find
> everybody on this list very nice and ready to help but we email regularly
> and I find it is working out well. He told me to shorten the LONG (geezz
> 12-15 Foot) primary wires, focus on the RQ cylinder gap, and get some good
> RFI dealyopies to filter line noise going into the ac feed.
> 
> Things are comming together with everyones help.
> 

Sounds like these changes should help... Keep us posted.

<SNIP>

> >Using high voltage chokes may reduce coil output somewhat by impeding
> >the tank cap charging process. However, they shouldn't prevent the coil
> >from operating unless you're running with very wide gaps and were just
> >barely firing the gaps prior to adding the chokes. Although chokes will
> >help protect your neons from internal breakdown, they won't do much to
> >reduce
> >radiated HF noise.
> 
> Good, I tried them and the coil put out nothing however they were built for
> a laser. I will keep to the basics right now.

A single-layer 5 - 10" long of 24 - 28 AWG on 3" PVC will provide ample
choking on the HV leads.  

<SNIP>

Kevin,

You're providing more clues in each post...
Since your neighbor is picking up your coil on his hard-wired phone, and
on his computer speakers, it sounds like you're getting conducted RFI as
well as radiated EMI. 

Since your caps are still tied across your transformer, the transformer
secondary is forced to oscillate with the RF on the tank cap when the
gaps fire. You are coupling a large amount of RF back through your
transformer and into the 120 Volt mains as a result. The transformer
case should be connected to your dedicated RF ground, not to the AC
mains ground. 

The EMI filters going to the primary of your transformer need to be of
the type that filter BOTH the hot and neutral sides (there should be an
inductor in series with each line), since both will pick up
interference. Individual filters can be used on each line as an
alternative. 

In a post to Fr. McGahee you said, in part: 

> I have my caps across the neon outputs and two dinky series gaps on
> each HV line to the primary. I am getting results with this  
> configuration but as everyone has told me I will blow my neon. WHat is > going to blow it, the caps are not a dead short, when I move to the 
> traditional method of putting the caps in series on one sire and the 
> gaps on the other I get zero results and the gap glows with a orange 
> flame arc.

If you're only getting a flaming arc, then there's a problem with the
hookup. You want the gaps connected across the transformer output, and
the caps connected in series with the Tesla Coil primary. The series
combination of the primary and tank caps should then be connected across
the gap. From the description above, and the behavior of your gaps, this
does _not_ sound like the configuration you used.

Make sure you're actually connected in the following manner and try
again. This configuration works very well once you've got it properly
connected. When the gaps fire, they shunt high power RF away from the
neon's outputs. This extends transformer life as well as cutting down on
interference.
 
                SW
     -----------||------
          |    Caps     O
          o             O
   To     o GAPS        O   TC
  Neon    o             O Primary
   HV     |             O 
 Outputs  |             O 
     -------------------      
     

Safe coilin' to you!

-- Bert --