The connection diagram represents a resonant circuit, with spark gap (F), condenser (C)and Tesla coil. The condenser consists 30 x 30 cm of 10 layers of aluminum foil, the dielectric was glas of windows with 0,1 cm. thickness. The electrodes of the spark gap were of brass. The secondary coil (Sek) was a 50 cm high PVC pipe with 7 cm. Diameter wound copper wire of 0.02 cm. Thickness. The primary coil (Pr) consists of twelve turns copper wire of 0,3 cm. Thickness. The oscilloscope shows a declining swing with a base frequency of 250 kc. For better isolation the secundary coil was painted several times and poured into commercial plexiglass. Instead of a spark inductor I used some oil burner transformers (T) parallel for producing the primary voltage (10,000 volts, one touch with this current, 50 a.c., can be lethal !!!) Old ones are very cheep available in Germany by Heating installateurs. Only components or materials were used, which are accessible also to childs and young people. The touch of metal sections of the primary circuit during the operation of the Tesla coil is lethal!!! Here voltages of more about 10,000 V step on with high ampere. As well as a touch occurs, breaks down the resonant circuit and the life-saving skin effect extinct. The reproduction should take place only under guidance of experienced electrical engineer or physics teacher.
"we set now the secundary coil of the transformer again to their workstation, connect the
two secondary clamps with two thick, isolated wires, from whose
free ends we remove the covering on approximately 1 cm length,
and switch the inductor on. If we collude then the room, then
we see resplendent light bunch out-shooting from the wire points.
If we bring the ends closer of the wires each other, then soon
a violent spark discharge begins. Under loud rattling long sparks between the wires estimate.
If one blows into the space between the wire points, then the
sparks resolve themselves into silver-shining flame arks, which
consist of a network of thick and thin spark threads. Now we put
the lower secondary clamp at earth, by connecting them by a wire
with gas-oder the water pipeline. As soon as the inductor is switched
on, large, blue lighting up light bunchs spray perpendicularly
outward from the clamp sitting above on the secundary coil.
Now we fasten 50... 60 cm are enough, bright copper wire of approximately 3 mm of strength in such a way in the heading clamp of the secundary coil that it perpendicularly is. The free end of the wire is isolated by taping with insulating tape or by an attached porcelain button. The other secondary clamp is grounded. If one switches the inductor on, then horizontally running bluish jets shoot out from the whole wire. If one removes the isolation at the point, then horizontal unloadings become weaker, but a blue, finely branched out light tree in the point of the wire, which up-grows freely into air and and varies slowly, shows up. We replace the wires by two rings made from bright copper wire, from which than the other one is somewhat larger.
The jets ignore then between parallel to each other the standing rings and to form a lighting up truncated cone. If someone touches the heading clamp of the secundary coil of the transformer with a Geissler tube, which one holds in the hand, then the tube lights up brightly, although it is connected with a pole only. The tube mostly even already lights up to it in the peculiar light, as soon as it is brought closer to the transformer.
We set two large metal plates (or into
coils of wire soldered wire nets) on our isolating stands, which
we set up to 30... 50 cm far from each other far away (the disks
are to be parallel), connect the connecting terminals with the
secundary coil and switch the inductor on. If we hold then a Geissler
tube into the space between the two disks, then the tube lights
up brightly. The attempt succeeds also with electrodeless tubes.
These attempts show that the whole space between the two disks is interspersed
by strong electrical fields. Also behind and over the disks the
light phaenomena occur.
While one must guard, as we know, much, the secondary clamps of a spark inductor to touch, if one does not want to carry heavy paralyses off, one can touch the secondary clamps of a Tesla transformator calmly with both hands. One will not feel anything. The reason for this is situated in the fact that the Tesla currents does not penetrate at all because of the high frequency into the body, but outside around him runs. If one touches the one secondary clamp with the hand and if one stretches the index finger of the others, which one protected by a metallic thimble or a short piece brass tube, against the second clamp out, then for a long time, violently rattling spark bundles between fingers and clamp skip. If one lets the sparks strike directly into the hand, someway then fire-wound-similar violations can develop."