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Re: Help...I'm having a lot of problems here...
to: Kent & Kim
Actually this is a great learning lesson for the youngster. In engineering
in the real world you carefully calculate the time required to do a
project --- then double it.
You capacitor is a DC capacitor and will not work properly at high frequency
(RF). You need a capacitor rated for high voltage reversals to do the job.
A quick solution would be to either fill some plastic tupperware (large
ones) with salt water as interior conductor and then coat outside with
strips of aluminum cooking foil. This will work but efficiency is very
poor.
The spark gap is connected directly across the transformer output terminals.
The cap is connected from the "high end" of the sparkgap to the tuning tap
on the primary. If your transformer is single ended (one bushing) then you
can connect other end of spark gap and capacitor to ground. If your
transformer is "floating" (2 HV bushings) then you have to keep everything
in the primary circuit insulated from ground or it will just be shorting
out.
If his project is due this Thursday I would suggest a few "all nighters" and
change the project to: Transformers -- What They are and How They Work.
Then you just need the ignition transformer and a few wire "coathangers" on
insulators (plastic soda pop bottles are ok for short notice). Form a 12
inch high V shape with 1/8 inch at bottom and 3 inches wide at top. This is
a climbing arc and was used for early lightning arrestors. They strategy
could save your project and get you a good score on the science fair.
The 10 kV, 25 mA value you listed is a standard value for Oil Burner
Ignition Transformer (we call them OBIT's for short).
We've seen others on the list trying to make a TC in a few weeks or less so
don't feel bad. It's a learning experience.
You can also obtain a free set of plans for a nice TC by sending me a $3.20
stamped priority mail envelope --- self addressed. My address is 10700 N La
Reserve Dr, Ste 20105, Tucson, AZ, 85737.
Our website located at www.ResonanceResearch-dot-com
Best regards,
Dr.Resonance-at-next-wave-dot-net
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Tuesday, February 16, 1999 2:31 PM
Subject: Help...I'm having a lot of problems here...
>Original Poster: "Kent & Kim Schaffer" <santoken-at-bright-dot-net>
>
>Hello all...
>
>About six months ago my step son and I decided to build a TC for his
science
>fair project. Boy, was that a mistake...
>
>First I'll tell you that this is my first coil project, so I'm sure we've
>made a lot of mistakes in our design. I think that one of my biggest
>mistakes is that cap we are using (I thought I would try to save some time
>and money).
>
>Power source:
>
> Furnace transformer or NST (I'm not sure):
> -10KVA
> -25 milliamp
>
>Cap (set back for a good laugh):
>
> -12x 2KVDC .01 uf ceramic caps soldered in parallel for a
>total of 24KVDC
> -submerged in mineral oil in plexi box
>
>Spark gap (another joke):
>
> -plexi box with three adjustable gaps in series
>
>Primary:
>
> -3/8" copper tubing
> -ID 7.7"
> -Wire spacing ..875"
> -5.5 total turns
> -wound flat (0 degrees)
>
>Secondary:
>
> -4.2" diameter (thin wall PVC drain pipe)
> -21" long winding
> -22 ga wire - enamel coated
> -shellaced before and after winding
>
>Toroid:
>
> -4" dryer duct
> -12" diameter center of tube to center of tube
>
>Now here is the problems we're having:
>
>After hooking up the cap the way all the schematics show I get no discharge
>at the spark gap at all. BTW, the way I read the schematics, one terminal
>of the cap attaches to the output of the transformer and the other attaches
>to the ground. Now, if I attach the cap in a series (one terminal input,
>the other output) I get spark at the gap.
>
>I have gotten absolutely no discharge at the torid whatsoever...sure does
>light a flourescent tube nicely though :-)
>
>Does anyone have a suggestions...I'm sure some of you must! Your response
>is greatly appreciated, since the science fair judging in Thursday...Yes,
>this Thursday.
>
>Kent
>
>