Changes to Coil (fwd)
---------- Forwarded message ----------
Date: Wed, 29 Jul 1998 22:38:00 +0930
From: Mark Finnis <mefinnis-at-medicine.adelaide.edu.au>
To: tesla-at-pupman-dot-com, USA-TESLA-at-list.iex-dot-net
Subject: Changes to Coil
Malcolm (& list in general),
Per our discussion off the list, I have replaced the primary with copper
tubing cf. the copper-coated steel. This hasn't made any real difference
to output, but the primary no longer gets hot, so I assume this equates to
less energy loss.
Tried Terry's gap, as stated in previous post to list, but had troubles
with oxide in the gaps so went back to large diameter copper tubing gap
(1.2mm x 4 gaps + fan) which stays quite cool & has best performance to
Still can't get sparks much past 3 ft. Given set-up & results from others
on list, would have thought I should get a little better.
2 x NSTs 15 kV / 60 mA
Protection = 2 x 1k resistors / 330 pF cap per HV line plus safety gap
- cap from junction of two resistors to earth
Primary cap = 0.025 uF rolled P/E (measured 0.022 uF)
Primary 6mm (0.25") copper tube, tuned at 7-8 turns.
- level with secondary bottom winding
- initially had some overcoupling (racing) but settled with
more acrylic spray-paint ;-)
- spacing 45mm (1.75") primary-secondary
Secondary = 160mm diameter / PVC former 5 mm thick
Wire = 0.8 mm x 770 turns over 700mm height.
Toroid = 18" x 6" "polished to perfection !!"
RF Earth = 3 x copper-coated steel pipes 15mm by 1m
Have ordered larger toroid (8" torus / 24" outer diameter) which will
Have found some tungsten electrodes from a welding repair shop (3 pairs) &
am starting spark-gap mark 5 ....
Any suggestions from the experienced ones welcome !!
Please remember I'm not in the EE field, so I don't have test equipment & I
can't test quenching etc., can only judge improvement by the gold standard
how far back I have to stand :-)
Still ....... having a lot of fun & driving the wife nuts ......
Mark Finnis Hm: 61 8 82895205
Staff Specialist Wk: 61 8 82224000
Intensive Care Unit Fax: 61 8 82236340
Royal Adelaide Hospital Mbl: 041 23242268