Making your own tesla coil
The devices described on this page may cause lethal
electrical shocks or serious injury! Any adaptation of the described devices
will be at your own risk!
Some time ago I came across a book named "Elektrotechnik für Jungen"
('Electrical Engineering for Boys') published in 1947.
First I was interested in building a spark inductor which was described in
the book, but gave it up,
as coiling up 10 km of wire didn't seem to be very exciting.
There was also a description for constructing a tesla coil, but it used
the spark inductor as high voltage supply.
Then I got a high voltage transformer which was used as ignitor in an old
oil heating. It transforms normal 230 V AC to 10 kV at max. 20 mA
But as I had forgotten about the tesla thing in the book, I just played
with the transformer itself (and nearly killed myself).
A year later I started studying physics and was inspired by a demonstration
of a tesla coil during a lecture.
I got the book again and started building.
As capacitors I 'borrowed' two glass jars from my grandma, on which I pasted
aluminium foil to obtain Leyden Jars. The primary coil was made of 5 turns
of thick (2 mm) copper wire, the secondary was coiled on a paper
tube. Even simpler was the spark gap, it just consists of a metall plate
and a pointed screw. These parts are connected this way:
Note: It is better to swap spark gap and capacitor (i.e.
spark gap in parallel to transformer and capacitors in series). This causes
lesser stress for these parts.
The measures of the parts in detail:
Transformer: prim. 230 V AC sec. 10 kV AC at max. 20 mA
Capacitors (Leyden Jars): 1. inner diam.: 9 cm, height
covered with alu foil: 14 cm; 2. inner diam.: 10.5 cm, height covered with alu
foil: 17 cm (together 2.7 nF)
Primary coil: diam.: 10 cm, height: 13 cm, turns: 5
Secondary coil: diam.: 4.5 cm, turns: 300
Note: the spark gap shown in the overview is now replaced by this one:
Spark Gap (scheme)
Spark Gap (photo)
Coil in action
Close-up of the corona
Discharge tube made by my father after my plans
(well my father is a glass-blower)
from the book mentioned above, which I published in a student paper
here in Heidelberg (German), HTML-Version
from the same book concerning the spark inductor (German),
- Article from Harri Suomalainen
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Created by Christoph Baumann May 1997
Last change: Aug 11 2014
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