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Re: Big conical TC
Hello Skip and all,
You said:
>I believe that Bert Hickman asked if there are any big conical TCs
>around. Some time ago I believe I was at the Palomar Observatory in the
>Los Angeles area and visited the museum which was at the site on top of
>the mountain. They had a conical TC which if memory serves me was about
>6' or 7' tall. I believe it was 1/2 of a two coil system. Also again if
>memory serves me I think the single coil which was on display put out
>about 10" sparks. Sorry I don't have more info. Perhaps someone else is
>familiar with this coil and can tell us if it still exists and more
>importantly, if it still works.
You may be thinking of the Griffith Observatory coil in Los Angeles.
It is described in TCBA News V5, #1 PP 6-7, and an earlier TCBA News
article I can't locate right now. It was originally built in the 1920's
as two vertical orientation conical coils, and was operated as a half wave
system. It was used for vaudeville demonstrations originally. Because of
lack of space, only one coil was fired in later years, after it was donated
to the observatory. The single coil was rebuilt in the middle 1980's. It
put out about 4 foot arcs. Looking at a photo, the secondary was perhaps 5
feet tall with a base diameter of about 2 1/2 feet and upper diameter of
perhaps 18 inches. The article says there were 292 turns on the secondary,
with an operating frequency around 120 kHz. There is a small 10-12 inch
sphere on top of each coil. Four feet of spark is not terribly efficient
for the 3.5 kVA of power used to fire it.
Regards,
Mark S. Rzeszotarski, Ph.D.