# FW: 3 Secondary Coils

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Sent: 	Sunday, June 22, 1997 3:01 PM
To: 	Tesla-at-pupman-dot-com
Subject: 	3 Secondary Coils

I made 3 secondary coils exactly the same physical size but each coil is
wound differently.  All coils are wound on 4" PVC pipe 13.5" long.  The
power supply is 15K 30 ma.  Cap = .01 uf.   I am using a Richard Quick spark
gap .025 each gap x 8 gaps. The high humidity here may have some effect on
the length of the spark output.  It has rained every day for 4 weeks except
yesterday.  It has rained all day today, humidity is 100%.  With all this
water the ground system should have a good connection.

Secondary coil # 1 is 4.5" dia x 13" long.  #24 wire.   600 turns.  12284
uh.  548 KHZ.  16.6 ohms.  Close wound single layer.

Secondary coil # 2 is 4.5" dia x 13" long.  #24 wire.  600 turns.   12284
uh.  548 KHZ.  8.3 ohms.  Close wound.   2 coils each 600 turns with one
coil wound over the other.  The 2 coils are connected in parallel.

Secondary coil # 3 is 4.5" dia x 13" long.  #24 wire.  300 turns.  3071 uh.
1096 KHZ.  4.1 ohms.    2 wires wound side by side close wound.  Each coil
is 300 turns.  The 2 coils are connected in parallel.

Test # 1.  The primary is flat 1/4" copper tubing 1/4" spacing.  Toroid is
5" x 11".

Secondary coil #1 the primary taps at turn 7.  Output spark = 9"

Secondary coil # 2 the primary taps at turn 7.  Output spark = 9"

Secondary coil # 3 the primary taps at turn 2.5.  Output spark = 6"

The primary tapped at turn 7 on both coil 1 and 2 proves that the inductance
did not change by connecting 2 secondary coils in parallel.

I would have guessed the primary would have tapped at turn 3.5 and not 2.5
on coil # 3.  I retested this again to see if I made a mistake.  Resonance
frequency is definitely primary tap turn 7 for coil 1 and 2 with no spark
output at all with the tap at turn 6 or 8.  Resonance frequency is
definitely primary tap turn 2.5  with reduced spark output at 1.5 or 3.5 and
no output at 1 and 4.25

Test #2.  The primary is 30 degree, not flat.  3/8" copper 3/8" space.
Toroid is 4" x 16"

Secondary coil # 1 the primary taps at turn 10.  Output spark = 12"

Secondary coil # 2 the primary taps at turn 10.  Output spark = 12"

Secondary coil # 3 the primary taps at turn  5.  Output spark = 8"

The primary tapped at turn 10 on both coil 1 and 2.  Again this proves that
the inductance did not change by connecting 2 secondary coils in parallel.

Secondary coil # 3 the primary tapped at turn 5.   Secondary coil 1 and 2
the primary tapped at turn 10.  This proves that the inductance of 300 turns
(2 coils 300 turns each in parallel) is half of 600 turns (2 coils 600 turns
each in parallel) or (1 coil with 600 turns).

This makes me wonder if I should wind my 10.625 x 32" coil with # 20 wire or
4 layers of # 24 wire.

# 20 wire, 948 turns, 149.8 KHZ, 68890 uh, 24.7 ohms.

# 24 wire, 1486 turns, 95.6 KHZ, 169344 uh, 95.3 ohms or 23.8 ohms with 4
layers.

After reading the recent post (4 layer coil) I had to do this test to prove
to myself that it really works. I also needed to know the advantages and
disadvantages of this.  Each layer has to be wound, coated with polyurethane
and dried before the next layer can be wound.  The 2nd layer is much harder
to wind than the 1st layer.  There are 4 times more labor involved in the 4
layer coil and if it performs better thats great.  A primary for 4 layers of
# 24 wire will be 1/3 larger than a primary for # 20 wire using the same LC
circuit capacitor.  I like the higher inductance of # 24 wire and I like the
higher frequency of the # 20 wire.  The goal is maximum spark output so I
think maybe 169344 uh is better than 68890 uh.   Is there a point where
increased inductance no longer increases the performance of a coil?   Now my
question is where does inductance reach its peak performance?   A good
mathematician could take some figures from several proven coils and
calculate the point at which increased inductance has no noticable increase
in coil performance.

humm.

Gary Weaver

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