Re: Micro Tesla Coil design

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-qwest-dot-net>" <f-h-at-c.dk>

Dan,
something is wrong, here

The smaller the core, the more turns you need to get the required
inductance. That`s why small transformers are a bigger pain in the butt,
compared to bigger ones that have fewer turns of more handleable thicker
wire.

10-20 primary turns sounds more like a 60 _k_Hz transformer

Cheers, Finn Hammer

Tesla list skriver:
 >
 > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
<dhmccauley-at-spacecatlighting-dot-com>
 >
 > Actually, that is still a bit too large.  This size transformer shouldn't be
 > difficult to wind.  A simple E-core (non-ferrite) should do it at 60Hz and
 > per my ANSOFT
 > simulation, the primary only needs about 10-20 turns with the secondary at
 > about 200-400 turns for 20:1 to step-up.  Low current of course figuring
 > about 5-10mA at
 > 1000V-2000V.
 >
 > Dan
 >
 >  > Rolling your own HV transformer is certainly not my idea of fun.  Larger
 >  > bug zappers typically contain a 4kV/9mA or thereabouts current limited
 >  > transformer somewhat larger than your fist.  I should think that would be
 > a
 >  > good fit for a palm-top coil.  They're pretty common at flea markets
 >  > (more-so in the summer), and ebay generally has many.
 >  >
 >  > One thing to watch though is some bug zapper transformers (BZT's??) 
have a
 >  > potted secondary winding (a good thing), but within the potting is a
 >  > ceramic cap, in parallel with the secondary (bad), to zap the bugs that
 >  > much harder.  You may need to do some precision drilling to remove 
that. I
 >  > haven't yet looked at how easy it is to remove the current limiting
 > shunts.
 >  >
 >  > Gary Lau
 >  > MA, USA
 >  >
 >  >   > Original poster: "Mccauley, Daniel H by way of Terry Fritz
 >  > <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
 >  >   >
 >  >   >
 >  >   >
 >  >   > I'm soon to start designing a microcoil.  The goal of this project is
 >  > build
 >  >   > a conventional tesla
 >  >   > coil as small as possible and still work.
 >  >   >
 >  >   > Has anyone had experience building one of these things? I know I saw
 >  > someone
 >  >   > building a palm sized version
 >  >   > on the internet before, but have long ago lost that link.
 >  >   >
 >  >   > Some questions:
 >  >   >
 >  >   > 1.  I'm going to have to build a mini 60Hz step-up transformer from
 >  > scratch.
 >  >   > What should the minimum voltage
 >  >   > output on this be?  I was thinking of having at least a 1kV to 2kV
 > output
 >  > at
 >  >   > 60Hz.
 >  >   >
 >  >   > 2.  Ballasting:  Since this transformer will not have current
 > limiting,
 >  > what
 >  >   > type of ballasting could I get away
 >  >   > with.  I guess at this size (and at the sacrifice of a few volts) I
 > could
 >  >   > use a resistor or even wind a small
 >  >   > inductor on the primary side of the transformer.
 >  >   >
 >  >   > Dan
 >  >   >
 >  >   >
 >  >   >
 >  >
 >  >
 >  >
 >  >
 >  >