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LAN_403

Avalanche

Fri Sept 29 2006, 11:31PM

Registered Member #103 Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845

Here's my latest creation, although it isn't quite finished yet.

Flyback powered SGTC, using the ZVS circuit and a large flyback. 2" diameter secondary. It's supposed to be a portable demonstration unit that can be powered from a car battery. More info on my site!

Hazmatt_(The Underdog)

Mon Nov 06 2006, 06:16AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Here's My SGTC Tesla coil operating with a 12/60 NST, 40KVDC Doorknobs, and lovely output streamers.

video:

Here's a larger picture of a test setup:

I am studying the effects of sympathetic breakouts.

ragnar

Tue Dec 05 2006, 05:04AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

This SSTC was designed to run at 13.56MHz, but its actual operating frequency shifts from ~12.7 to ~14MHz depending on its surroundings. The discharge makes no noise of its own, and is audio modulated by FM.

Plasma is VERY dense, VERY hot.

This is the DS waveform, 40nS/20V per div., supply voltage is 32V.

Tesladownunder

Sat Dec 09 2006, 03:50AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Here is a mini TC made from the components of 1 microwave oven. This was a competition that I set up but no-one won. I did eventually complete mine some just 9 days late. Shown here with 1/2 inch sparks only but best in development has been 1 inch and plenty of scope for improvement with better design.
The details:
Power supply is the MOT. This needs current limiting and this is achieved with a 150nF capacitor and the voltage is boosted by a one stage multiplier using the MOT diode to give 4kV peak. Note that power is taken off across the diode not across the cap to get the voltage multiplier effect. Hey what's this about a 150nF cap? Where is that in a microwave oven? Well that is the key to this project. The 1uF 10kV DC mylar and oil cap (that is in all non-inverter MO's) needs to be taken apart and unwound. Lengths of the multilayered dielectric and foil are taken out and cut to length. It took about 10 feet of the windings to make 150nF. This is perhaps only 30% of the total. New electrodes were added.
Tank cap. This is a 1nF cap. The technique is similar but I retained the original electrodes from the cap to use in this section as they were better suited to a high current. Construction of this cap was different in view of the much higher voltage/current and frequency stresses. It used about 30% of the length of the cap windings. The plates were only about 1 foot long by 2 inches, however I used two sections of foil/dielectric between them. The foil was not connected and was kept to equalise voltage stresses. All in all something like 12 layers of mylar and 2 foil layers separate the main electrodes.
Being mylar they do warm up a bit.
Spark gap This is two aluminium electrodes (from the frame of the MO fan) bolted to part of the MO timer circuit board with all the components and printed circuit ground off. It really needs another section to give better quenching.
Primary is the MO transformer 6V winding which is heavy copper. This is stuck on to the 3 legged wheeled frame that the glass food tray sits on and rotates.
Secondary former is the cardboard internal cardboard insulation from the HV cap. It was washed but became a bit soft but still usable.
Secondary windings use wire from the fan motor and less than half was used. The hot glue didn't stick the cardboard former together properly and the windings slipped and overlapped. I have had some interturn shorting (and may still have) so I can't really push the power much without a rewind. No idea how many turns.
Toroid I did try winding lots of turns of wire on the fan blades but it didn't improve the performance. so I just left the metal mesh spacer that sits on the output of the magnetron for a nice colour.

Pics show the cap construction, overall plan and sparks close up. Not fabulous performance but the proof of principle is there are plenty of opportunities to do better.

Peter

1165636217 10 FT14 Moteslaprizecompleteopensetupb

1165636217 10 FT14 Moteslaprizesparkscloseb

Tesladownunder

Sun Jan 28 2007, 02:02AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

This is my "Fill your backyard with sparks coil"
It is an addition to the toroid with a 7ft long rotating breakout point. When view in a time exposure the streamers and sparks are spread over a wide area. Photo shows a 13 second exposure.

Peter

Thomas

Fri Mar 02 2007, 05:37PM

Registered Member #120 Joined: Fri Feb 10 2006, 07:07AM
Location: Westchester New York
Posts: 83

Here's two pictures of my SSTC V1. It has a 2.5" x 13" secondary, the primary has 8 turns and it uses positive feedback from the H-bridge. It's pretty much derived from Richie Burnett design, except for a few circuitry changes.

Brett Miller

Wed Apr 04 2007, 09:34PM

Registered Member #593 Joined: Tue Mar 20 2007, 12:32AM
Location:
Posts: 50

Here is my second SSTC. It is basically the natural progression of my solid state path so far, that being the well traveled Steve Ward formula. I would like to thank Steve for taking time to answer my questions on many occations.

I built a version of his MicroSSTC, but used an isolated logic supply and built a remote shielded interrupter. Next I decded to upgrade to a half bridge of IRFP260N's 200v 50a. Basically, this is almost an exact copy of Steve's MiniSSTC. Unfortunately I haven't yet procured a second spool of 30awg, so I am currently using the 3.5" (9 cm) diameter x 8" (~20 cm) winding length secondary that I wound for the MicroSSTC. I found that spark length doubled with the addition of my John Freau 6 x 1.75" toroid. Currently my max output is about 5-6 inches (13 cm), but I expect longer sparks after I upgrade to a lower frequency secondary. I have only had this working for a couple days, so other tweaks will need to be made, such as optimizing coupling and number of primary turns.

Here is a picture of the system in its current incarnation, sitting up on my old 6" disruptive coil table. The other picture shows a braidlike bundle of sparks at high bps/prf. The best thing about having a coil like this is being able to vary the spark characteristics in real time via a remote interrupter.

Brett Miller

Wed Apr 04 2007, 11:38PM

Registered Member #593 Joined: Tue Mar 20 2007, 12:32AM
Location:
Posts: 50

Here's my first SSTC. It's a very small ISSTC based on Steve's MicroSSTC. However, I made a few small but significant changes. I used the UCC37322 non inverting driver so I could use a remote interrupter. Also, I made the regulated 12v supply for the 555 and UCC seperate from the supply that powered the MOSFET so I could try running it off of any supply I felt like trying. This has been a lot of fun and a learning experience. The interrupter I built is similar to the one on the Class E SSTC that Steve shows on his schemtic, however, the only pots I had available at the time were two 100k audio tapers. Still, the interrupter provides a good range for both PRF and On-Time.

When I was doing the initial testing for this coil, the only resonator I had in the lab with an Fres low enough to achieve osciillation with this driver was my vttc secondary. It's 19" (~48 cm) of awg 26 on a 3.5" (9 cm) form. I got around 2.5" (6.5 cm) sparks with this secondary (air streamers with the interrupter, and pulled arcs in CW mode) using a 30v transformer rectified and smoothed with 6600uf. The cap that has given the most success is a panasonic poly 1600v .0033uf. I have tried several mosfets with more or less similar results: IRFP460, IRFP250, IRFP260N. This is a fun little driver and a great introduction to solid state coiling. Thanks and much credit to Steve Ward here.

-Brett

Brett Miller

Thu Apr 05 2007, 02:31AM

Registered Member #593 Joined: Tue Mar 20 2007, 12:32AM
Location:
Posts: 50

Here is my first and only (so far) vttc, although it has been used as a platform to test several tubes now. It was originally designed to be a single 833A system, inspired by John Freau and Steve Ward to name just two of the many who have had great success with the robust 833.

In this picture I have the 813 installed with plate choke (I do not use one with the 833A).

I should also mention that the lexan ring around the top of the primary form actually came in handy on one occation and was first seen on one of Chris Hooper's tube coils. Also moving the feedback coil up to about the midpoint of the secondary winding has really helped tuning in quite a few configuraions, hence the longer than traditional primary form. In the picture above, you can see the RCA 833A socket still on the base of my vttc test stand. I have managed 21" sparks (at 60 pps -- no staccato) with both the 833A and 813 in this system. Recently I dropped in a 304tl and got 13" sparks with no tweaks to the system, but the plate was running very hot. A grid leak resistance change was almost certainly needed. Too busy with my SSTC projects lately.

Here's photo of the system managing around 20 plus inch (51 cm) sparks with a single 813 tube:

Specs:
-------
Secondary: 19" Winding length (AWG 26) 3.5" diameter PVC form
Topload: John Freau 6" x 1.75"
Primary: 28 turns AWG 12 stranded close wound on a 6" dia PVC 12" high...capped with lexan ring (the Hooper hoop).
Feedback: 25 turns AWG 23 magnet wire on a HDPE slideable form
Tank Cap: Two Yish doorknobs 1.1nf x 2 in parallel (50kv)
Grid Leak: 1.1nf yish (50kv) in parallel with 6k 50w power resistor
PSU: One large MOT...shunts removed, with 3uf MO cap doubler with 12x 1n5408 diodes with another doorknob for bypass.

This has been a very robust system. It's been a lot of fun even without staccato, which I plan on throwing together later this year sometime.

-Brett

Brett Miller

Thu Apr 05 2007, 03:54AM

Registered Member #593 Joined: Tue Mar 20 2007, 12:32AM
Location:
Posts: 50

Here is my first TC. It was, of course, a disruptive coil.

This 6" coil was inspired first by the fact that at the time I was conceiving this project (around late 1999) I was highly influenced by the web page of German coiler Stefan Kluge, who also used a 30 degree primary for high coupling. In retrospect, I should have probably used a flat spiral configuration, nevertheless, I never had a single primary strike in spite of the lack of a strike ring. Over a period of several years, I used this system as a test bed and to make component comparisons. I even attempted to write a paper contrasting the performance of my TCBOR style static gap, with a multi mini static (quench) gap built by Terry Fritz which provided a 1st notch quench.

Specs:

Transformer: France 12/60 NST
Cap: Resonant .012uf (commercial caps and MMCs were tried....I prefer MMC)
Spark gap: TCBOR just like in the old R.Q. .doc file...1.5" cu pipe electrodes.
Primary: 14 turns 1/4" cu
Secondary: 6" diameter 24" winding length AWG 23 HPN Green Magnet Wire
ACR (lower toroid): 11.75" x 2.75"
Toroid: 4" x 17"

With the old Panasonic style MMC I got up to 45 inch streamers and arcs to ground, so I was right on my Freau number for 720va...of course back then I didn't have the nice amp clamp I have now, so in reality things may not have been so efficient as it sounds on paper.

Here's a spark photo:

I don't know if this will end up as scrap or not. If I built another disruptive coil I would like to have a secondary which boasts a lower Fres. Most of the tank circuit (transformer and caps) have been traded away and I'm using the stand (not shown in pic) as a table on which to solder my sstc projects. Such is progress I suppose.

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