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[TCML] caps and efficiency
Bart,
That's a pretty neat little coil.I like the "beer bottle" caps. How are they for efficiency? Dr. Jeff helped me make a TCBOR type homemade oil-filled cap back in the mid nineties for my table top coil. I compared this highly effiecient cap to a series-parallel arangement of 100 doorknob caps approximatley equal in capacitance to the tho TCBOR cap recently. Here's what I found:
Doorknobs: (690pf-20kv times fifty caps in parallel) times two banks in series ran at 12kv-60mA full throttle for over an hour. No heating, no flashover. very lossy, only about 1/2 the performance of the TCBOR cap. The reason I ran so many caps in parallel (MMC) was to overt the possibility of heating up, as the ceramic doorknobs tend to drift as much as 20% as they heat up. I was considering using one bank of these caps in my 833C plate as the main tuning cap. As it stands, I aquired a nice mica transmitting cap, so I used the ceramic cap bank as RF bybass with a large VLF Plate choke instead.
Here is a picture of the coil and progress so far: http://www.drspark.org/images/tubecoil/Dsc_0004.jpg
The coil runs in three modes: (1) AC/MOT-pulsed with SCR for conventional "sword" shaped sparks. (2) Pure DC cathode-modulated using pulse input from Audiotesla MKIIc Tesla coil controller (I use this mode to play guitar, keyboard and Theremin through the tube coil) Output sound in this configuration very closely resembles that of a DRSSTC coil. (3) Pure DC grid-driven with 100 watt PLC amplifier/oscillator/modulator. (I use this mode to connect to a Sony Walkman CD player.....very interesting) I am presently working on phasing control to explore improved operation and efficiency. This is a prototype coil. It allows me to mimic ideas I would like to try out on a solid state coil. Difference is that the tube coil can handle alot more abuse (accidents and oops') than its solid state counterpart....less tempermental.
Woo
> [Original Message]
> From: bartb <bartb@xxxxxxxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Date: 5/3/2008 10:33:19 AM
> Subject: Re: [TCML] bipolar coil
>
> Hi Woo,
>
> Dr. Jeff must be using a small cap size for the turns. This is an actual
> bipolar coil also, unlike what I think Kris is building. Dr. Jeff's
> bipolar is a nice little coil! I built one similar in size, although it
> was not used as a bipolar coil, but rather a hv source for a Seibt coil.
>
> http://www.classictesla.com/seibt/Img_2870.jpg
>
> I've been wanting to turn this thing into a self-contained bipolar coil
> (however I need to replace the wooden primary runners with something else).
>
> Take care,
> Bart
>
> dr.hankenstein@xxxxxxxxxxxxx wrote:
> > Kris,
> >
> > Here is a picture of Dr. Jeff's small bipolar coil: http://www.drspark.org/images/jeffbipolar/Dsc_0185.jpg If I recall correctly, he's using a 9kv / 30ma neon sign xfmr with a Sangamo mica transmitting capacitor and a 5-break stationary spark gap. Tuning doesn't seem to be very critical. Secondary is rather small, maybe 2" x 12" or so. Small coils are alot of fun!
> >
> > Woo
> >
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