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Primary Question



Original poster: "David Kyle by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-kyleusa-dot-com>


Hi All,

 

After seeing my 1.35KVA Tesla coil in action, my son is interested in a smaller
scale model for a school science project. Never needing an excuse to make
sparks I immediately agreed and started working on a design with him. It is
also a great opportunity to use up a number of the spare parts I have floating
about my shop. 

 

Obviously this needs to be very low power so for safely considerations I am
going to make it battery operated. For power I plan to use an old reproduction
model T spark coil my mother bought for me at Pep Boys around 1968 (she thought
my strange hobbies a safer alternative to drugs). The secondary will be 3.25
inches diameter thin wall PVC with 18 inches of 26 gauge wire (~1000 turns).
For the tank I acquired some very nice small pulse caps (value as used .0125 -at-
40KV) with the help of someone from this list. It will use a simple static
spark gap with some left over tungsten rods from my SRSG. I have a beautiful
little 6 inch spun aluminum toroid I bought from a member of this list for the
final.

 

My question concerns the primary and what shape to use. Ease of construction
would suggest a vertically wound concentric primary. Alternately we could build
a 30 degree cone or the now popular flat spiral. What are your experiences with
these primary shapes in small, low power coils? What is the most efficient
choice for best output?

 

Also while I have your attention does anyone know the approximate value of the
high voltage one normally sees from a model T coil when run at 12 volts
(current draw is about 1.5 Amps and it makes a pretty healthy spark)? 

 

Thanks for your help,

Dave

 

<http://home.austin.rr-dot-com/dkyle/tesla.htm>http://home.austin.rr-dot-com/dkyle/
tesla.htm

 

=========================================
Dave Kyle
Austin, TX USA
Email: dave-at-kyleusa-dot-com