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Re: Dwell time, etc

Original poster: BunnyKiller <bunikllr@xxxxxxx>

Hey Kevin...
dwell time is the time lapse that encompasses the time that the rotating electrodes are in line with the stationary electrodes ( to be more realistic ,the time that the arc starts and then quenches across the gaps) 

if my math is right... ;)  heres a how to find the time
find the radius the electrodes are sitting at on the disc, 2X it for the dia and then Pi it to find circumference.... multiply that number by the RPM of the motor and you get linear measure per min... divide that by 60 and you get linear measure per second... now we are getting closer
multiply the dia of the electrode by 3 and then divide that by the linear measure per inch 

for example  your electrodes are 4 inches away fron the center of the disc
this gives you an 8 in diameter....  X Pi gives you    25.1327
that times 1800 rpm  gives you 45,239.005 linear inches per minute
divide that by 60 and you get 753 linear inches per second
and your electrodes are 1/2 inch in dia thusly 3 times that is 1.5
sooo   1.5 / 753 = .00198 seconds    or about 2 millisecs....
so what does this number do for us?? lets go back to the begining at about 30 revs per second which equates to 1 rev per .033 seconds now we can deduce that since we are using .002 secs to arc, that leaves us .031 secs to recharge the cap for the next bang... but realistically, the arc drags out further than the end of the electrode and increases the dwell time thus reducing the time to recharge the cap... in some cases by an additional .015 seconds leaving us with the paltry moment of .024ish seconds to recharge... you need a healthy transformer to fill a big cap in that time limit...
seeing that you are planning on a larger dia disc, that will decrease dwell time and since you are using 2 different dia electrodes you will increase the dwell time a tad... not much to be concerned about... 

as far as power and size   toroid to pipe an easy 8 feet+

Scot D



Tesla list wrote:


Original poster: "MakingLightning" <MakingLightning@xxxxxxxxxxx>


What is dwell time and how does it affect your coil?

I always thought that nice big electrodes on a spark gap was a good thing,
but was recently told that it would increase your dwell time.

I just wound an 8" coil
and am planning on using 2 big 0.1 uf 90kv (20kv working voltage) custom
made Condenser Product caps in series (I bought them about 12 years ago when
they actually sold things like that to us, then went through a divorce and
am finally getting around to using them, they were about $1000 apiece
then!),
a 5kva 14.4kv pole pig,

and was planning on making a 12" rotary gap with 8 - 1/2" electrodes and 4 -
9/16" stationary electrodes in series (better for quenching?).

I have a 60a 240v variac and a 200a welder for controlling the power.

Anyone have an idea of what length of sparks I should expect from this
setup? (free air and to a ground rod)

Any other comments that you guys have on this setup would be greatly
appreciated.

Kevin