Re: 12 inch spark, 1 inch flame.
>Rather than cut and hack up those poor bobbins, why not just
>wind 3 identical transformers. As long as you phase them properly they
>can be put in series for higher voltage or parallel for higher
I thought about that but it does mean more winding -
instead of a 2*24 primary, I can wind a 2*8 primary. :
(same flux density and 60% of the induction)
2*8 primary, 120 turn secondary,
or 3 transformers
2*24 turn primary, and 120 turn secondary.
(3 primaries in //, 3 secondaries in series.
or maybe 2*8, 40 putting the primaries in series.
On balance I thought it was simpler to make one
large transformer - I also wanted to try this because
when I start to push towards 2 or 3kw - then I may need
a couple of big transformers :)
I did consider using a handful of cheap surplus
ferrite rods say stack a pile of 1/2" diameter,
7" long - to get say 2 or 3" diameter - wouldn't need
that many turns - pity about the efficency.
Got some cheap surplus toriodal transformers - guy claimed
he hadn't tested them - blew a fuse then discovered that
instead of the two primaries wired in series they had all come
with one primary shorted out. One cut and they were working.
I'm away now for 3 weeks, France then Scotland -
to see our parents and old friends in Aberdeen.
Alan Sharp (UK)