[Prev][Next][Index][Thread]
Loading, quenching, and surging
----------
From: D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Saturday, March 07, 1998 5:31 PM
To: Tesla List
Subject: Re: Loading, quenching, and surging
to: John
One reliable and easy way to check the quenching of any system is to place
a sharp ground rod a fixed distance from the coil at normally the 90-95%
max striking distance. Turn the coil on. If the streamers connect
immediately and solidly from the toroid to the ground electrode while the
primary sparkgap electrodes are in the "cold" -- not yet warmed up to
normal operating temp, and, then the spark stays at this distance, this
indicates good quenching. If the spark discharge dramatically "shrinks" to
60-70% of this distance then the quenching is not adequate as the sparkgap
electrodes are heating up rapidly to red hot and the secondary spark starts
diminishing in length. In systems with tig welding rods (usually 1/8th
inch dia) this effect is more pronounced. Even in smaller coil systems
using 1/2 dia brass rod (for heat conductivity) with large 1/2 inch dia
tungsten electrodes -- this offers remarkable improved performance as the
sparkgap is quenching (switching off rapidly) better and trapping more
energy in the secondary coil to "ring". Chuck Cook uses large surfaced
tungsten electrodes in his smaller oil coil system which is quite
impressive with no secondary spark reduction (as demonstrated at Ed
Wingate's recent Teslathon). You are probably familar with this test but I
posted it to assist new coil builders -- since you were on the topic of
quenching. Also blowing some compressed air thru the gap and noting if the
sec spark "shrinking" or "extending" effect occurs can tell you something
about how effectively you are quenching the primary sparkgap. If the air
blast helps then just add a small 150-200 CFM blower in front of your
electrodes as Chuck does.
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Loading, quenching, and surging
> Date: Friday, March 06, 1998 10:01 PM
>
>
> ----------
> From: FutureT [SMTP:FutureT-at-aol-dot-com]
> Sent: Friday, March 06, 1998 8:04 AM
> To: tesla-at-pupman-dot-com
> Subject: Loading, quenching, and surging
>
> All,
>
> Many have discussed the importance of spark loading for good quenching,
> and I think my latest coil demonstrates this is an intriquing way. I'm
using
> a two gap sync rotary at 60 BPS, and obtaining 45" sparks at 600 watts.
>
> Often the sparks are shorter than 45", and at these times, the gap arcs
> are very bright indicating poor loading and subsequent poor quenching.
> Then as the coil runs, a random spark often reaches out a little farther,
> which causes the loading to improve, which improves the quenching,
> making the gap arcs dimmer. As the quenching improves, the extra
> energy going into the arc lengthens it even more, which in turn improves
> the loading and the quench. So a positive feedback condition is occuring
> which eventually propels the spark out to the full 45", and the gap arcs
> are very dim by this time, indicating excellent quenching. Finally, the
> spark hits the measuring wire, the loading is adversely affected, and
> the gaps brighten, and the process is free to begin again. In addition,
> the longer sparks may be improving the tuning of the coil, adding still
> another factor to the positive feedback loop. The loudness of the coil
> also increases during the long spark, good quenching times, reflecting
> the extra energy going into the streamers.
>
> This process may be occuring in many coils, but may not be so
> pronounced. It is possible that the 60 BPS break rate slows the
> process so it is more easily seen. It is also probably important to
> use a somewhat marginally quenching gap to make the process more
> noticeable. I've noticed that when I use better quenching series
rotaries,
> the gap tends to run at a more constant brightness, and the sparks tend
> to be more equal in length with less surging. I actually find the
surging-
> type operation gives a more interesting and impressive display, and some
> visitors who saw the coil in operation strongly agreed. I've noticed
that
> many large coils tend to surge in this way. Maybe the characteristic
> is enhanced in large coils, or maybe the quenching was marginal in
> those coils. I think this surging effect is at least a partial
explanation
> for those *rare long sparks* that people refer to.
>
> I've seen this surging in some of my previous coils, but to a lesser
> degree. I'd be interested to hear if anyone has seen this effect in
> their coils. Comments welcomed as always.
>
> John Freau
>