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RE: Core Material

Subject:  RE: Core Material
  Date:  Wed, 7 May 97 21:27:46 UT
  From:  "Robert Davis" <Davis_Lewis-at-msn-dot-com>
    To:  "Tesla List" <tesla-at-pupman-dot-com>


>
Subject:      Re: Core Material
       Date:  Sat, 03 May 1997 16:31:11 -0700
       From:  Bert Hickman <bert.hickman-at-aquila-dot-com>
Organization  Stoneridge Engineering
         To:  Tesla List <tesla-at-pupman-dot-com>
 References: 
            1

Tesla List wrote:
>> 
>> Subject:   Re: Core Material
>>   Date:    Fri, 2 May 1997 12:21:13 -0400 (EDT)
>>   From:    Esondrmn-at-aol-dot-com
>>     To:    tesla-at-pupman-dot-com, tesla-at-poodle.pupman-dot-com
>> 
>> In a message dated 97-05-01 18:20:51 EDT, tesla-at-pupman-dot-com >writes:
>> 
>> <<
>>  Hello Coilers,
>> 
>>  I am about to start building the secondary of my first (small coil), I
>>  have
>>  some Acrylic rod and thought of using this for the former.  Being soild
>>  I
>>  would be able to screw and bolt connections to the former.  I would
>>  think
>>  losses would go up slightly as opposed to sealed tube construction >but
>>  not
>>  enough to be a problem.  Would there be any other problems using a
>> solid
>>  plastic core?
>> 
>>  Also, I was thinking about half wave coils, not many people seem to
>>  build
>>  these.  Why is this?
>> 
>>  I look forward to receiving your replies.
>> 
>> 
>>  Rob Davis (UK)
>>   >>

>Rob, 

>How big is the diameter? The main prroblem you'll encounter is getting a
>high enough inductance since solid rods tend not to be very big in
>diameter. The fact that the material is solid or tubular will have
>minimal effect on circuit performance. What coil length and wire gauge
>were you planning on using??

>-- Bert --


I have 25mm (1") Acrylic Rod, 50mm(2") Acrylic Tube, 80mm(~3") Acrylic
Tube 
and can get 50mm Nylon Rod.  Teslac gives the following using 30swg wire 
(Diameter & Length in inches, Fres in KHz, Inductance in mH) :

Diameter   Length      Inductance   Fres     Loaded Q
2          7           5.126        1186     34.6
3          9           14.55        596.3    36.1

Teslac won't do the very small 1", I have seen a very small coil, it
looked 
about 1" X 8" but had a very small spark.

I will go for the 3" X 9" (the solid is a lot more expensive, I just
thought 
it might be easier in construction).  It will be a low power coil, maybe 
50-100 watts and I will probably go for a solid state drive on the
primary 
(probably MOSFET but I haven't decided yet), comments?

One other thing, am I correct in thinking that magnifier coils are
driven 
directly from the base connection of the coil?  If so does the power
supply 
have to supply a large current or large voltage to the base?

I look forward to receiving your replies.


Rob Davis, UK