RE: Coil schematics?

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi,

I should point something out about the "Terry filter" and circuits like it.  

When the sun is shinning, the birds are singing, and your coil is arcing
away happily you don't need a filter.  However, the filter was not designed
for "happy" moments...

When your caps explode, the rotary gap shatters, your secondary flames
up...  That is when the filter will protect your neon from damage.  The
safety gaps protect against over voltage when the main gap screws up for
reasons we keep inventing.  The new trigger gaps will add more to that list
of gaps failing to fire "because"...  The MOVs are also redundant until one
screws up the safety gap settings (and you know who you are! :-)).  Many
people get by fine without filters or safety gaps but they really know what
they are doing.  I think 90% of NST failures are due to over voltage, thus
the filter has two ways to stop that.  The RF filter stops signals from
getting to the NST that can only do bad things to it.  If you count up NST
failures with a filter and those where there was no filter, the numbers
will differ by two orders of magnitude.

The "Terry" filter was designed to protect the NST no mater what was
connected up to it.  If your could is working perfectly, the filter is not
doing much.  If your coil is have a disaster, your NST may be all that is
left...  Being a "universal" filter, it may have features that may not make
sense for a particular coil.  Of course, modifications to the original
design voids the warranty ;-))  Although, you can certainly substitute
parts you have on hand since they are not super critical.

With the "Terry" filter and an input fuse protecting the NST, there is no
known way to destroy the NST.  Without any protection, NSTs seem to die
like flies...

Before some asks (again :-))), the filter is at:

http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg

Cheers,

	Terry



At 10:45 AM 10/4/2001 -0400, you wrote:
>The schematic showed the safety gap wired directly in parallel with the
>main static gap.  If the safety gap is set for 25kV and the main gap is
>set for 21kV, I can't think of any reason for the safety gap to ever
>fire, since they're both connected to the same point and see the same
>voltage.  The main gap will always fire first, so the safety is simply
>redundant.
>
>There may be some physical distance between the NST secondary and the
>main gap.  It has been observed that a safety gap may indeed fire
>independently of the main gap.  The reason for this has not been
>researched, but the distance from the NST to the main gap may have
>something to do with it.  If the NST is seeing a higher voltage than
>that present at the main gap, then you want the safety directly at the
>NST.
>
>Regards, Gary Lau
>MA, USA
>
>
>Original poster: "Steve White by way of Terry Fritz
><twftesla-at-qwest-dot-net>" <slwhite-at-zeus.ia-dot-net>
>
>What is the reasoning here? Both locations are electrically identical.
>
>
>> Original poster: "Lau, Gary by way of Terry Fritz
><twftesla-at-qwest-dot-net>"
><Gary.Lau-at-compaq-dot-com>
>>
>> I think that you want the safety gaps wired directly across and
>> physically close to the NST secondary (i.e. on the left side of the
>> resistors), not in parallel with the main spark gap.
>>
>> Gary Lau
>> MA, USA
>>
>> >Original poster: "mbarbani by way of Terry Fritz
><twftesla-at-qwest-dot-net>"
>> ><mbarbani-at-yahoo-dot-com>
>> >
>> >Hi Neil,
>> >
>> >Here's a schematic of my coil.
>> >
>> >http://hot-streamer-dot-com/temp/Teslaschem.jpg
>> >
>> >It's got all the "normal" required parts that most
>> >coilers use, plus one part that's my own addition.  Take a look at
>the
>> relay on
>> >the primary side of the NST.  It is there to switch power to the NST,
>> because I
>> >like the idea of being able to run the coil with a hand-held
>> pushbutton, but
>> >don't like the idea of switching 120v in my hand directly to the NST
>> even
>> >though the button is well insulated. It actually switches power to
>the
>> relay,
>> >which in turn gives power to the NST, thereby reducing the current
>that
>> is
>> >going thru the pushbutton in my hand.  Both common poles of the relay
>> are
>> >ganged to give extra switching power to the NST.
>> >
>> >Good luck,
>> >Marc B.
>>
>>
>>
>>
>
>
>