[Home][2015 Index] Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)? [Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

# Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)?

I use the formula:

spark length (inches) = 1.7*sqrt input power (watts)

For example a coil that uses 1000 watts should
produce a 53.7" spark.  However this formula only
works for very efficient coils.  To get this sort of
efficiency it's usually necessary to use a synch
rotary spark gap at 120 bps, and a suitable LTR
sized capacitor (for NST systems).  Such a coil
would work well with a 16" toroid.  Toroid size tracks
with spark length as given by the formula.
Figure the toroid diameter should
be about 0.3 times the calculated spark
length.  Or use the formula:

toroid diameter (inches) = 0.5*sqrt input power (watts)

Note that my formula uses a square rule for
spark length vs. power input.  The older idea
of using a more linear relationship probably
came about because many small old coils
tended to be inefficient and therefore gave a
false impression.  The toroid formula will
also only work right for an efficient coil.

For example my TT-42 coil produces a
42" spark from an old "robust" 12/30 NST.
The system draws about 800 Watts.  The
formula suggests 48" sparks, but I only
get 42".  However I have to crank up
the input power using a 140V output
variac to get the 42" spark, so the NST
is probably saturating some at that point,
and becoming less efficient.  NST's can
draw a lot more than their rated power
in a Tesla coil running at 120bps.
Over-volting them also makes them
draw more power.

Your 6" x 25" toroid should be able to
produce 80" sparks (assuming a
suitable Tesla coil design and power
input.  I don't think going to an 8"
There must be something else
limiting your spark length.

John

-----Original Message-----
From: Timothy Gilmore <tdg8934@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Mon, Apr 6, 2015 8:09 pm
Subject: Re: [TCML] Tesla Coil parameters list like Tesla Map software (i.e. spark length, secondary height, # of NSTs)?

I found Jeff Pennoyer's
site:
http://www.webring.org/l/rd?ring=teslaring;id=107;url=http%3A%2F%2Fhome%2Ecomcast%2Enet%2F%7Epennoyer%2FJeffPage%2Ehtml

At
the bottom there is this list which falls in line with what I was
looking for
on spark length:

APPROXIMATE SPARK LENGTH VRS POWER INPUT CHART
SPARK LENGTH
POWER INPUT
6 - 8 INCHES 300 W
8 - 12 INCHES 500 W
12 - 18 INCHES 700 W
15 -
20 INCHES 1000 W
18 - 24 INCHES 1200 W
24 - 30 INCHES 1500 W
30 - 36 INCHES
2000 W
36 - 45 INCHES 2500 W
45 - 56 INCHES 3000 W
56 - 64 INCHES 3500 W
64
- 72 INCHES 4000 W
72 - 80 INCHES 4500 W
80 - 90 INCHES 5000 W

So using (2)
15kv 60mA NST provides about 1850 W. I am getting at least 36
inches and many
times 48 inches or more of sparks from my 6"x25" toroid:

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla

• Follow-Ups:
• References: