Re: Solid State - progress.


Made some progress with the transformer.

I'm using an ETD49, material 3C85. Primary is 11 turns of
2 * 1mm side by side, then on top repeat the primary winding
twice, So that each primary consists of 3 * 1mm in \\.
(2 identical primaries for push pull. Secondary is a single
0.9mm wire, there is room on the bobbin for 3 layers. A
ratio of about 7.5 to 1. The higher ratio's give the bigger
sparks, even though, because of current limiting I can only
use about 50% of the cycle.

In use good for 5 min runs, some heating in the core,
windings are hotter - so I have probably gone as far
as I can with reducing the primary turns. Its taking
about 500 - 600 Watts at 210kHz so its not surprising
that it is heating! With a grounded electrode I can
draw a 5" arc from the discharge point.

Took it into school today (Juniors 400 aged 8 to 11
whom I take for Assembly). I don't know if they
made my theological leap to the power of the Holy
Spirit - but it may have sparked an interest in 
science. Totally mystified when I got an 8' flourescent 
tube to light up in my hands. (about 5' away from
the coil). Lots of interest afterwards.

Lots to do, and I may get the time, church winds
down a bit in the summer, and I've got a student
assistant for 8 weeks. 

Now for that 400v full bridge.

Alan Sharp.