RE: Core Material

• To: tesla-at-poodle.pupman-dot-com
• Subject: RE: Core Material
• From: Tesla List <tesla-at-stic-dot-net>
• Date: Thu, 08 May 1997 08:21:42 -0500
• Approved: tesla-at-stic-dot-net

Subject:  RE: Core Material
  Date:   08 May 97 05:10:52 EDT
  From:   Alan Sharp <100624.504-at-CompuServe.COM>
    To:   "INTERNET:tesla-at-pupman-dot-com" <tesla-at-pupman-dot-com>


Rob Davis wrote:
>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?

Rob why not use 4" PVC pipe - about L12 for 3m from a builders
merchant - I've used black pipe quite happily but others on the list
point out that carbon is used to colour it - doesn't seem to be
a problem at 500W.

A 3"x9" coil will have a lower induction and much higher frequency
- say 500kHz - tricky with mosfets due to switching losses. 100 - 200kHz
is more usual. Driving a primary with Mosfets is not easy. High voltages
are
reflected back from the secondary to the primary - ZAP. I blew a lot of
FETs
trying this!

>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?

Yes - at present I'm using a 200v supply with a push pull
design, 1:9 output ratio - therefore 1800v, 500W supply -
run continously it would consume 2kW. Makes the input
impedence of the coil about 2K ohms. (This coil is a wound
on a 5 gallon bucket.

Have fun

Alan Sharp (UK)

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