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Re: RE: [TCML] Toroid Problems
Nicholas -
You stated that your toroid was made from "dryer duct" material. Can you confirm that this is really convoluted aluminum HVAC ducting (formed from heavy gage aluminum foil, like disposible pie-pans are made from), and not the thin aluminized polyester material wound around a coiled spring core? You need to use the HVAC duct material, which comes compressed but is stiff enough to hold out at 90 degrees without sagging. The usual "dryer duct" material is metallized plastic film over a wire core (like a "slinky" toy), and is NOT conductive. I have seen several first-time coilers get confused by the "dryer duct" material, which may look similar to the HVAC duct material if you're looking at a photo on the internet. Quick check: take an open flame and apply it to the material. The aluminized polyester material will instantly melt,laving only the inner spring, but the flame will have no effect on the aluminum HVAC duct.
Otherwise, it looks like you've generally done your homework. Of course, to state that you've got "about" 950 turns on the secondary implies some lack of precision, and theres no way that you know the resonant frequency is actually 243.344 KHz unless you have actually measured it. You might want to go back and carefully measure the exact number of turns in an inch of winding length, and re-calculate the total number of turns. Also, is your secondary tightly wound, with essentially no gap between adjacent windings? Even small turn-to-turn gaps can have a significant effect on total turns count of a long secondary. \
Regards,
Herr Zapp
"Nicholas J. Goble" <ngoble@xxxxxxx> wrote:
I did not wire together various components and hope they'd work
together. I did my research and used the calculators listed on
deepfriedneon.com. Here are the specs for my coil:
Transformer: 9/30 transformer
Spark gap: air quenched, multi-electrode spark gap. There are five
copper pipes, 3.5 inches in length that make up the electrodes. All
the gaps fire beautifully. I got the plans off this website:
http://www.kronjaeger.com/hv-old/misc/scotsgap/index.html
Capacitor: I used the "Capacitor to Transformer Match" calculator on
DeepFriedNeon and found that I needed a capacitance of .0088uF. The
Tesla Map construction guide told me that I needed to multiply that by
1.414 to get my LTR capacitance of .01244uF. I bought 12 942C20P15K-F
caps that are rated at 2000V and .15uF. I wired them in series to get
a capacitance of .0124uF. Correct me if I'm wrong with these
measurements.
Primary: 1/4" OD copper tubing spaced 1/4". Inner diameter is 6.5". I
did 13 turns just in case, but my calculations show that I only need 11
turns to have the correct inductance. With 11 turns, the inductance of
the primary is 40.147uH.
Resonant Frequency of Primary: The capacitance is .0124uF. And the
inductance (with some tuning) is .0345mH. That makes the resonant
frequency 243.332kHz
Secondary: For my secondary, I wound a 4.5" diameter PVC pipe that was
sprayed NUMEROUS times with acrylic spray sealer. I sealed the ends
with some PVC caps that I bought at Lowes and used caulk as a glue. I
wound the secondary with 24 AWG wire. It was 21" tall. All in all,
there were about 950 turns of wire. I sealed the form after winding
too. Inductance is 19930uH and self cap is 8.316pF.
Toroid: Explained in my main post, capacitance is approx 19.137pF.
Resonant Frequency of Secondary: The capacitance of the toroid is
19.137pF, and that of the secondary is 8.316pF. Combined, the
secondary circuit's capacitance is .000021453uF. It's inductance is
19.930mH. The resonant frequency is 243.344kHz.
There are the specs. I thought that all those calculations were
correct. What could be wrong? There are no wires on the inside of my
secondary. If the secondary wire sparks with no toroid, could it just
be a problem with my top load? Is it to big? Is my connection not
good? I really want to get this thing working well. With a toroid.
Any solutions or diagnoses?
Thanks
Nicholas Goble
Lau, Gary wrote:
>I see no mention of what you're using for a capacitor, or primary coil.
You have verified that the primary and secondary resonant frequencies
match, right? It does sound like they don't match with the toroid in
place, but YOU need to gather all the numbers and verify this. One
can't just throw together an NST, capacitor, primary and secondary
coils, and hope it will all play together. If any one of them is the
wrong value, it will be out of tune and won't work.
>
>Regards, Gary Lau
>MA, USA
>
>> -----Original Message-----
>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
>> Behalf Of Nicholas J. Goble
>> Sent: Monday, August 04, 2008 1:38 PM
>> To: tesla@xxxxxxxxxx
>> Subject: [TCML] Toroid Problems
>>
>> Last night, I fired up my coil for the first time. I set everything up
>> and made sure that all the connections were solid. When I plugged the
>> NST in, the spark gap fired, but there were no sparks coming from the
>> toroid. I tapped the entire primary, but got no streamers. At a few
>> points, the safety gap was firing, so I guessed that the caps were
>> working. I thought that the only thing that could be wrong was the
>> toroid. When I disconnected the toroid and ran the coil, I got
>> streamers and some corona coming from the tip of the secondary wire. I
>> was able to tune the coil without the toroid. I got 5-6 inch
>> streamers/sparks from the wire.
>>
>> Here are the specifications for my toroid:
>> 4" height
>> 17" outer diameter
>> 9" inner diameter
>> I took two flimsy 9" pie pans and glued them together. Then I wrapped
>> 4" aluminum dryer duct tubing around it and secured the ends together
>> with duct tape. I secured the tube's connection to the base with caulk
>> on the rim of the pie pans. I took some aluminum foil and wrapped it
>> around the duct taped section, and connected that to the base (pie
>> pans) with more duct tape. I drilled a hole in the middle of the pans
>> and attached a nut and bolt. I sanded off most of the enamel of the
>> end of the secondary wire and secured it to the middle of the toroid
>> with the bolt.
>>
>> My secondary is 4" dia and 21" tall. I'm using a 9/30 NST. Can anyone
>> diagnose my problem? I dobut that my toroid is too big. If anything,
>> I thought it would be too small. I used a nail to create a breakout
>> point on the toroid while it was running and it still failed to produce
>> streamers. What's the problem?
>>
>> Thanks
>>
>> Nicholas Goble
>
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