Hi David,
Yes, my small SSTC in the video runs in two swichable modes; 1) direct antenna feedback at about 300Watts, and 2) VCO direct drive at about 200Watts. With feedback drive it is self tuning and couples well to the environment. This long of tube with such high ionization voltage presents a heavy load of about 200-240Watts, depending on orientation and proximity. This mode was shown in the video I linked. VCO drive allows for high fidelity audio modulation (see my channel's other videos for examples) but EM field loading causes an impedance mismatch as the secondary is pulled out of resonance. This serves as a current limiting feature which is useful for demonstrations where the unwary hand/tube might stray too close. Consequently this mode of operation is no good for driving high loads, such as my plasma tubes.
Complete schematics, instructions, and build files are available for free on my website for anyone who wishes to use them. I do have direct feedback controller boards available for sale still too. I can provide information on the VCO drive for anyone who wishes as well but I did not do up documentation on it yet due to the terrible design engineering of the 4046 PLL chip, who's VCO I am making use of. There is no formula for determining the VCO frequency based onRC parameters, and the user must interpolate values from a low resolution graph in the datasheet. I've found a new VCO chip that works far better, but it only comes in the TSOT-23 package, which is MUCH smaller than a single grain of short-grain rice! Perhaps in the future I'll do up a proper design document for the new VCO, for now it is too much hassle and very little interest has been shown so far.
If I might ask a favor of the list; is the formatting of my responses messed up to anyone? It appears on my end that word wrap is disabled. I REALLY hate win8.1's new Mail system/program and its lack of formatting controls. I am currently typing this reply in notepad and I will paste it into the mail program/app to see if that helps. Thanks!
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Hi Matt,
Thanks for the clarification and the cool video link. One thing of interest I noticed on your video is how your tube "loads" the output of your TC when it ignites and the discharge plasma of the coil is noticeably diminished.
David
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Sincerely,
Matt Sig Giordano
Sigurthr Enterprises
www.SigurthrEnterprises.com
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