[Prev][Next][Index][Thread]
Re: Questions Questions
Subject:
Re: Questions Questions
Date:
Thu, 27 Mar 1997 10:36:35 -0500
From:
"George W. Ensley" <erc-at-coastalnet-dot-com>
To:
Tesla List <tesla-at-pupman-dot-com>
At 08:47 AM 3/26/97 -0600, you wrote:
>Subject:
> Re: Questions Questions
> Date:
> Wed, 26 Mar 1997 06:48:22 -0800
> From:
> Bert Hickman <bert.hickman-at-aquila-dot-com>
>Organization:
> Stoneridge Engineering
> To:
> Tesla List <tesla-at-pupman-dot-com>
> References:
> 1
>
>
>Tesla List wrote:
>>
>> Subject:
>> Questions Questions
>> Date:
>> Tue, 25 Mar 1997 00:06:10 -0500
>> From:
>> "George W. Ensley" <erc-at-coastalnet-dot-com>
>> To:
>> tesla-at-pupman-dot-com
>>
>> Hello,
>> I have been attempting to optimize my 6" coil with some success. What i
>> have
>> noticed is that the coupling coefficient seems to vary a good deal. Any
>> number of factors seem to affect it, breakout, toroid height, toroid
>> size,
>> coil height, etc. I am using K=(Fh-Fl)/Fr to find K is this correct?
>>
>> It has been interesting to note that while using a large toroid, 7"x 30"
>> which was difficult to break out, the system exhibited all the signs of
>> over
>> coupling. When a small tab was added to assist breakout, all of the
>> signs
>> went away and the best spark to date was achieved.
>>
>> Some how i get the feeling that the signal generator and the O-scope
>> aren't
>> telling me all i want to know. What is the k of the system while in
>> operation? How can i check it?
>>
>> -------------
>>
>> The best thing that ever happened to my TC was when a fan failed and i
>> melted down my RQ pvc gap. I was forced to build a new gap using a shop
>> vac
>> a plastic 5 gallon bucket and some 5/8 copper pipe. It's noisy but my
>> sparks
>> went from 48" to 67" with no other change.
>>
>> I have observed a wave shape change in the output of the coil that is no
>> doubt the results of better quenching. It is now a single hump with a
>> fairly
>> rapid rise and slower ring down. Previously a double hump was evident
>> with
>> the second being much smaller than the first but still causing the event
>> to
>> last almost twice as long.
>>
>> I have been attempting to follow the discussion on optimal quenching but
>> lack some basics. What was i seeing? Is that the beat notch or was it
>> just
>> the gap trying to fire again? How are these measurements made? What is
>> the
>> test setup?
>>
>> ------------
>>
>> I was pleased to see Richard Hull on The Learning Channel tonight with a
>> big
>> TC running in the background. Interesting stuff water.
>>
>> George............
>
>
>George,
>
>Congratulations!! From the sounds of it, your new gap IS quenching at
>the ideal point. Your secondary waveform in that case will rapidly rise
>to the maximum, and then come bak down relatively slowly (dependent on
>how "big" the streamers are). The added sparklength is due to keeping
>more of the energy in the secondary rather than coupling a portion of it
>back to the primary and losing it in the gap.
>
>Regarding coupling, now that you have a good quenching gap, you can try
>increasing the coupling by raising the primary relative to the
>secondary. The low-power measurements of Fh, Fl, and Fr above are a good
>approximation. The trick now is to experimentally find the best point of
>operation. Based upon your excellent results already, I'd recommend
>changing the height by no more than 1/4" at a time. Each time, run the
>coil in a dark room and look for any signs of overcoupling (usually
>inter-turn flashovers) while slowly ramping up the power level to the
>maximum. If you start seeing "Christmas tree" corona between the top of
>the secondary winding and the strikerail below, lower the toroid a bit.
>Adjusting "k" is a little tricky, since increasing the coupling also
>makes the gap more difficult to quench, and once you start getting
>"double humps" again, you may also start getting inter-turn flashovers.
>For a fixed vacuum gap configuration, there's no way I'm aware of to
>maximize "k" versus the the rest of your system other than trial and
>error.
>
>Once you reach the point of overcoupling, back off a bit, and start
>adjusting the tune a bit. Usually you'll need to increase the primary
>inductance a bit from "instrument tune" until you get best performance.
>Although this process may take a little time, you'll end up with a
>system that's running at peak performance.
>
>After doing all this, NOW go back and do a low power remeasurement of
>Fl, Fh, and Fr. With a little bit of luck, you'll be in the .18 to .23
>range. Sounds like you already have a kick-butt coil, but this will
>wring the best out of it. BTW, what are the other parameters of your
>system (input power, tank cap/primary size, and secondary /toroid
>size?). Again, congratulations - job well done!!
>
>Safe coilin' to you, George!
>
>-- Bert H --
>
>
>
Bert,
Thanks for the reply. I am beginning to see the relationship now. I did
some
scoping last night and found that the second hump is not completely gone
until i have max spark with the big toroid. Seems that loading does
makes
the quench better. Smaller toroids even in tune wouldn't do the job. I
did
note that off tune i would see 3 and 4 humps with the small guys.
I will cut some shims and work on the K as i recall it is close to one
of
the magic numbers now. But i keep playing with the toroid height to keep
the
strikes off the rail.
The Specs:
Neon Xfmr 12kv, 120ma
Primary 14 turns 3/8 spaced 3/8 at 30 deg.
Secondary 6.25 dia, 22ga wire, 26in winding
Capacitor CSI technologies .02uf at 50kv dc
Toroid 7" x 29.75" with a 1/4" tab to aid breakout
Resonance 145kc with toroid in place
K= .1724
I posted some jpgs a while back, the red ones, it just has a bigger
toroid
and a new base with wheels.
Max spark to date was 67" but i must admit i had the gaps a little wide
and
the voltage on the neon at 135vac. Probably took an hour off of it's 10
hour
life in tesla service.
George...
HAM=N4ZPO
SGMET=#244
FCC=PG-5-6642
erc-at-coastalnet-dot-com