Tesla ? coil - Griffith Observatory

From:  Dan Murphy [SMTP:danmurphy-at-1stnetusa-dot-com]
Sent:  Friday, June 05, 1998 6:48 PM
To:  Tesla List
Subject:  Re: Tesla ? coil - Griffith Observatory

Good memory, Terry -
        Having visited the Tesla Coil at Griffith Park recently, I can
attest to the accuracy of your description. Gene Waldo and I went there for
the specific purpose of viewing the coil, and watching it demoed. It does
indeed have a round discharge terminal at the top of its tapered secondary,
with 2 spikes on its circumference, right and left sides, to focus the
output. There are grounded plates mounted in the walls on either side, 4 or
5 feet from the terminus, to which the sparks fly unerringly. It uses a
rotary gap, I believe, but the only parts of the apparatus that can be seen
are the primary, secondary and terminus. Attempts to gain access to the
inner sanctum for a look at the power supply, etc, were unsuccesful. The
tour guide gives a canned speech about Tesla and the principles of the coil,
but it seemed like something he memorized, and he didn't really know all
that much about coils and their underlying principles. Still, it's a fun
show, lighting up neon and flourescent tubes with no wires, and
demonstrations of the skin effect. Still, nothing like KVA Effects and Brent
Turner, the Million Volt Man. Now, THERE'S a Tesla demonstration!
     As for the original Griffith Park coil, we were told it came from a
carnival, and that it was 60 or 70 years old. Nothing was mentioned about it
being half of an original dual secondary set-up. No one could shed any light
on the efficacy of the tapered secondary, other than it might lessen the
chance for arc-over discharge, as it isn't equipped with a strike rail.
Might have some effect on coupling, also. We decided it wouldn't be worth
the effort to build a tapered coil form for winding such a beast... But who
knows, maybe it is!

>From:  Bill Noble [SMTP:william_b_noble-at-email.msn-dot-com]
>Sent:  Thursday, June 04, 1998 11:45 PM
>To:  Tesla List
>Subject:  Re: Tesla ? coil - Griffith Observatory
>the coil at the Griffith Observatory (in griffith park, in the Hollywood
>hills) is half of an older coil - it is run daily for visitors.  There is a
>data sheet available on the coil - perhaps the observatory has a web site??
>I haven't checked for that.  The original coil had two tapered secondaries
>and the primary in the middle, if I remember the brochure correctly.
>And,yes, the coil is still there.
>-----Original Message-----
>>I've only been subscribed to this list a short time, but this is the first
>>reference I've seen describing a tapered secondary. It reminded me of the
>>I saw as a kid at Griffith Observatory, outside LA, I believe. I recall it
>>as having a flat spiral primary of flat copper strap, and a tapered
>>secondary with a round terminal with spikes on opposite sides. It
>>to the walls of the room, a few feet away. Does anyone know if there's an
>>advantage to tapering the secondary this way?