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RE: First light - sort of
Greets Ron And All,
> -----Original Message-----
> From: Tesla List [mailto:tesla-at-pupman-dot-com]
> Sent: Saturday, February 19, 2000 2:52 PM
> To: tesla-at-pupman-dot-com
> Subject: First light - sort of
>
>
> Original Poster: "Ron West" <ronwes1-at-juno-dot-com>
>
> I had somewhat puzzling results with my new coil last night. The first
> thing I should say is that I am building this coil in two stages:
>
> First stage, I built it with a VERY low power source (anyone familiar
> with the "Solid State Tesla Coil" plans in the Nov. '99 Popular
> Electronics? - 24 volt transformer stepped up by two auto ignition
> coils). I did this to learn the priciples and safety involved in
> building a coil and as an introduction into HV before jumping in with
> something larger. My coil has a primary with 11.5 turns of 1/4" copper
> tubing wound with inside diameter of 7" and outside of 18". Secondary is
> 4" coil form with 21.2" of 22AWG polyester-amide-imide magnet wire. Cap
> is two series-connected Glasmike mylar caps totaling 27,500 volts 25nF.
> Voltage out from the ignition coils is about 12KV but I have no idea what
> the current is. Torroid is 4" X 12" aluminum ducting. I went all out on
> my ground, I have 5 - 8' copper clad rods spaced at 8' interconnected
> with 4 AWG bare copper wire and connected to the coils via 2" wide copper
> strap.
That is exactly how I got started. Unfortunately they told us to run
the secondary wire inside the tube. Oops fine for now, but it will
short out when moving way up in power. I get about 7" to ground wire,
and can the only way I can get it to break out on it's own is without
the toroid and a re-tune. I used one car coil instead of two. I
also used a 12 volt transformer and a full wave bridge rectifier. I
also then regulated the 555 timers power to 5 volts, since the rectifier
is going to give us 17 volt peaks.
Ah nice grounding system you have. I only used a 4' piece of rebar.
>
> Second stage, to use the coil (primary and secondary coils and the base)
> as a "stepping stone". I plan to upgrade this to a 'real' coil with NST
> power source, MMC, improved spark gap, etc.
>
> I had expected to have 6" - 8" streamers (according to the article) but
> only got 4" sparks with some corona visible on a ground wire held near
> the toroid at about 6". This may be all this coil is capable of (and it
> may already be time to proceed with stage 2), but it brings up a few
> questions I hope somebody can answer.
I used a bigger storage capacitor than they suggest. I have 1 whole farad.
The full wave rectifier they suggest for the 24 volt transformer I think
is wasting half your power. That is why I went with the full wave bridge
rectifier.
I have now powered the coil with two other things. A 9kv-at-30ma about
the same spark length only a whole lot more of them. Oh I used a full
wave rectifier here like you used on the 24 volt transformer. Last
night I hooked up a old CGA monitor guts. Got the streamers up to 10"
now. I think the CGA power plant is running it with DC because it
operated with a slower bang rate than I expected, however I only have
to turn the variac up to 40 volts to get it started. I have to crank
the NST all the way up to full power to get anything to happen. The
CGA guts gives me some cool sounds when sweeping the variac up. Makes
it kinda more interesting.
>
> When tuning it seems to tune at (only) 4 turns. I had expected it to end
> up closer to 8+ turns. Is this somehow related to the low power, or is
> it simply a result of the frequency of the secondary? In other words
> when I change to my NST will I need to re-tune to more turns?
Wow only 4 turns, with a toroid about the size of yours mine tunes
in around 9 turns. My secondary is 28awg, 4.5" diameter and 17"
tall to give me approximately 1000 turns. I am going to try 24awg
on the next coil. Without a toroid my tunes in at 5 turns. I am
thinking maybe you need tighter coupling between the primary and
secondary. The inside diameter of my primary is 6".
>
> Could the torroid be too large or two small for the coil? I tried the
> coil without the torroid and the sparks were only about 1" in length
> instead of the 4". So the torroid does seem to be doing it's job, but
> maybe it could be more efficient?
You probably need to retune after removing the toroid. I am waiting
for a 1.5" x 6" spun toroid from John Freau. I will report what I
find with this toroid. I have purchased a 15kv-at-60ma to power this
TC with too. However I am holding off until I build the new secondary,
and a MMC. I will let you know how that goes as well.
>
> Thanks to everyone for a great list,
> Ron West
>
>
>
Glad to hear I was not the only one that tried out these plans.
It was a pretty good starting point and they left a lot up to
the imagination of the builder which made it a lot more fun.
Be careful if you move up in power. I don't think there is
very much amperage at all with the car coil system. I don't go
anywhere near the thing until I have powered down and triple
checked that all safety precautions have been taken. I was
reading in a old Navy manual that the amperage can up as much
as 300 in a resonant tank circuit. This probably requires one
to drive the circuit at resonant freq, which we don't usually
do since we have 60 hertz readily available.
Looking forward to hearing and maybe seeing your results.
Cheers,
Bill Parn