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Newbie's Coil
It may help some newer members of the list if I describd how I made my first
coil.
I was inspired by two books that must be long out of print, by an American
scientist by the name of A(Archie?) Collins, who was, I believe, a pioneer
of wireless telephony. They were: "Electricity For Boys" and "Fun With
Electricity." They are listed as "missing" in the British Museum.
Basically I made a capacitive discharge coil. Let's look at a schema of the
components.
-----------------------------------------------> <-------- <--------|
| high | | Spark < < |
|tension | | gap < < *
|source | Capacitor < <
| | | < < *
| | | < < |
---------------------------------------------------------- <--------|
Prim Sec
The high voltage was first supplied by a spark coil interrupted by a buzzer,
and in my second effort by a neon transformer.
It is also possible for the high tension to be supplied by an electrostatic
machine or, as has been mentioned in the list recently, by a fly-back
tranformer from an old tlevision. However, this means more circuitry.
For a capacitor, I first used two 2.5litre polythene bottles cut off at the
shoulder, and lined inside and out with aluminium foil up to just over half way.
I used polyurethane as the adhesive. A wooden lid with a brass bolt through,
with wire or fine chain hanging down to the inner lining and wire connecting
the high tension source to the "Leyden Jars" formed one side of the
capacitor, which was then connected to the spark gap. The outer coating was
connected to the end of the primary farthest from the spark gap and
earthed(grounded).
In my second one I used small panes of glass with lugged squares of
aluminium foil, the lugs being alternately laid left and right.
____
| |
| |
----------------| |
| |
| aluminium |
| foil |
| |
| |
--------------------
For the spark gap, two pieces of brass angles, tapped for two bolts and
screwed into dry hardwood.
The primary was made of 18SWG wire (1.22mm.), bare, and the secondary of
36SWG (.193mm.) plastic coated wire. I made a squirrel cage on which to wrap
the primary ,and 18SWG wire is a pig to wind, and I first used some 6mm.
dowelling on which to wind the secondary. All the wood was well varnished
with polyurethane.
If I haven't covered anything, shout out. It was pretty cheap to make.
Incidentally, has anyone used a Van Der Graaf machine for their high tension?
Have fun,
Joe.