WooHoo!!! Built and now just waiting for the toroid.

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Decisions decisions

Postby DJKOR » Thu Sep 19, 2013 1:32 am

stegu wrote:If anyone with really strong and impressive sparks at full power could post measurements of their primary and secondary resonant frequencies using a signal generator and an oscilloscope, it would be much appreciated and provide much more specific advice for the rest of us who are still struggling to see those 20" streamers.


I agree. It would be good to have some comparison data to work with. I'd be curious to see how jeffcrilly's figures look after seeing this video: https://www.youtube.com/watch?v=L_QOLx-6eXg

I'm kind of stuck trying to figure out which way to progress. When comparing my 6 turn primary + larger toroid configuration with my 5 turn primary with stock size toroid, even with my tuning off by the same amount, I seem to get different behaviour from it.

I actually felt more confident with the 6 turn primary and larger toroid configuration as I was getting a larger output at 50%. Therefore, I'd feel more confident playing with the secondary to match the primary rather than the other way around. Doing this means that I won't maintain the clean look of the original design with the stamped toroid though. Also, I'm still not sure of the effects of adding all this extra capacitance in the topload.

So I have now returned to my tried and tested and I think it is probably my best starting point based on everything I have come across:

Image

Image

http://youtu.be/wOS--nWR5c4

Also tested with a fluro tube placed at 20 inches away (give or take half and inch) from the tip of the breakout point to test to see if I could get some strikes with it. Looks like I could only get a couple.

http://youtu.be/kJNAOep43hQ
Last edited by DJKOR on Thu Sep 19, 2013 4:32 am, edited 1 time in total.
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Re: WooHoo!!! Built and now just waiting for the toroid.

Postby stegu » Thu Sep 19, 2013 3:01 am

Also, I'm still not sure of the effects of adding all this extra capacitance in the topload.


It's still only a few pF, so it's not a lot of extra capacitance in absolute terms, but a larger capacitance would mean a proportionally smaller peak voltage at the breakout point (I think) with the same amount of energy oscillating in the secondary circuit. I feel better tuning the primary coil than changing the capacitance of the top load, but any changes will have some impact on the output, and I don't have enough experience to tell which alternative is better.

It would be good to have a circuit simulator to play around with, one that gives at least qualitatively correct results, to test the impact of various methods for retuning. Has anyone made for example a PSpice simulation of a DRSSTC? I can run simulations, but I wouldn't know where to begin making one.
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Re: WooHoo!!! Built and now just waiting for the toroid.

Postby Bayley » Thu Sep 19, 2013 5:13 am

stegu wrote:
Also, I'm still not sure of the effects of adding all this extra capacitance in the topload.


It would be good to have a circuit simulator to play around with, one that gives at least qualitatively correct results, to test the impact of various methods for retuning. Has anyone made for example a PSpice simulation of a DRSSTC? I can run simulations, but I wouldn't know where to begin making one.


The problem is we don't have a good model of a streamer (especially a dynamic model), making it very hard to accurately calculate the output voltage.
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Some more song testing.

Postby DJKOR » Thu Sep 19, 2013 6:20 am

Thanks to the midi files from Moors7, I put another song through my oneTesla just because I wanted to hear something different. I ran the test at 50% mainly because I wasn't game to push it any harder even though I know it could go louder if I turned it up more. All I can say is that I was really on edge while running this in the fear that something would break. Luckily, it made it through the song and the primary was only warm to the touch afterwards.

https://www.youtube.com/watch?v=IBTltULZkUo
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Re: WooHoo!!! Built and now just waiting for the toroid.

Postby stegu » Thu Sep 19, 2013 2:49 pm

Bayley wrote:The problem is we don't have a good model of a streamer (especially a dynamic model), making it very hard to accurately calculate the output voltage.


I can see how that would be essential to making a good simulation. Hmm. I should mention this problem to one of my colleagues who at least ought to know a lot more than I do on this subject.
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Some additional figures

Postby DJKOR » Fri Sep 20, 2013 3:47 am

For record keeping purposes, I thought I would write down some additional current figures here based on the configuration in my most recent posts. This is also another thing I would like to see others with good functioning coils to post to gather some comparative data.

Supply voltage: 243 VAC
Supply frequency: 50Hz

Power Draw (Maximum value measured with inline meter):

Lowest : 0.14A
1/4 : 1.42A
1/2 : 2.18A
3/4 : 2.76A
Full : 3.35A

Edit: I was feeling game and cranked it to full power just to get a reading.
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Re: WooHoo!!! Built and now just waiting for the toroid.

Postby stegu » Fri Sep 20, 2013 4:00 am

Did you run the coil in fixed frequency mode, and in that case, at what setting for the frequency knob? The current draw varies more or less linearly with the pulse frequency.

Your current draw seems a bit high to me. My coil is now well tuned at 1/2 power, not full power, but in that configuration, it draws 1.5A from 230V mains at 50% power and 3.5A at 100% power, in fixed frequency mode and medium frequency.
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Further information

Postby DJKOR » Fri Sep 20, 2013 4:03 am

stegu wrote:Did you run the coil in fixed frequency mode, and in that case, at what setting for the frequency knob? The current draw varies more or less linearly with the pulse frequency.

Your current draw seems a bit high to me. My coil is now well tuned at 1/2 power, not full power, but in that configuration, it draws 1.5A from 230V mains at 50% power and 3.5A at 100% power, in fixed frequency mode and medium frequency.


Good point. I knew I forgot to include something. All tests I do (so my spark length testing too), I do in fixed frequency mode at the highest frequency setting. That way the only variable I can control on the interrupter is the power.

On that note, re-ran the tests at mid-frequency and have the following:

Lowest : 0.12A
1/4 : 1.03A
1/2 : 1.93A
3/4 : 2.40A
Full : 2.91A
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Re: WooHoo!!! Built and now just waiting for the toroid.

Postby stegu » Fri Sep 20, 2013 4:59 am

OK, interesting. Your current draw is definitely higher than mine at 1/2 and 1/4 power, but at full power it's less than mine. At minimum power your current is also lower, but that might be because almost no spark breaks out at lowest power unless the tuning is good enough. (I have a 1-2 inch spark at minimum power with my current tuning.) You seem to start out with somewhat bad tuning at low power but get better into tune at higher power, which is of course the way I would want mine to behave as well. What is your spark length at full power? Can we see an image or a video?
And also, if you post an image, can I include it in the "gallery of sparks" at the end of the tuning guide for which I published a draft just now in another thread?
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Even more "testing"

Postby DJKOR » Fri Sep 20, 2013 6:16 am

stegu wrote:What is your spark length at full power? Can we see an image or a video?
And also, if you post an image, can I include it in the "gallery of sparks" at the end of the tuning guide for which I published a draft just now in another thread?


You are welcome to use anything that I post.

Well... this is where things are getting quite interesting now. I have tried running it in both a darker area (good for video) or in the lounge room where I do most of my measurements however now I can't seem to get any really long sparks. The configuration of my coil remains the same as it did before I started playing around with it. Only thing I can think of is that the weather has gotten much warmer and slightly more humid than previous runs, but if those conditions are meant to improve the sparks... well I'm stumped.

Previous runs I have had the following:

DJKOR wrote:A quick test today showed that I was getting about 18.5 inch sparks at 50% power however it didn't look like turning up the power would yield anything larger. I'm not game enough to push the power higher in Fixed mode to really test if that is the case, so I will live with it as is in the meantime.

Image
http://www.youtube.com/watch?v=1s9Y5AwiWgw


So using the same measuring method, I ran the following and got about 17.5 inches. I ramped from minimum up to full power then wound down to just below 50% before turning it up to 50% after which I turned it back to minimum... in case you are wondering:

http://youtu.be/z6G39qvd-5o

Image

One thing to note, my spark don't seem to get longer as I went past 50%. I did however notice the note get a little "stronger" for lack of better word and the spark become a little beefier.

I also decided to give it a full power run with the following:

Popcorn - http://youtu.be/dMLiW9aAgB0
Paranoid - http://youtu.be/Mcb5Y9OiXTw

Edit: I was just running another song test and noticed that some songs tonight are producing better sparks than the fixed frequency testing where usually it is the other way around.

So...... I did a quick test with "River Flows in You" also thanks to Moors7. I felt a little uncomfortable running it for too long so thats why I only ran it for a little before winding it down. The primary did get a little warm to the touch after that. Not burning but it was like my old Galaxy SIII or iPhone 5 when under heavy load.

Excuse the camera going out of focus. Measuring from the tip of the breakout point, the closest part of the bulb (the outer edge, not the top) is 20 inches away.

http://youtu.be/DWyRpRYCJOM

Image

Edit 2: I was starting to feel more game after running the coil at 100% and not having it instantly fry. So I fired it up again this morning:

Mario: http://youtu.be/dbMgawbK2hs
Pirates: http://youtu.be/CdE_ERZQT8U
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My build thread: viewtopic.php?f=15&t=998 | 246kHz Primary / 267kHz Secondary
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