I did it, working coil! (and datalog)

Show off your finished kit here!

I did it, working coil! (and datalog)

Postby Freebee » Tue Nov 19, 2013 5:44 pm

Succes, at last!

Image
Arcs at about 1/3th power. Did not continue further yet.

I'm glad I'm able to post here, that's for sure. This thread is a) to show off and b) to provide data about my working coil. Also some kind of worklog to dump data for myself and anyone else, I guess. As of this moment I have to wait for my USB oscilloscope, so I can't provide 100% detailed information about this working coil just yet.

Building
I got my coil about three weeks ago, and I started soldering the same day. I got both of them done a few hours later, soldering is such a calming and satisfactory job, really. It was with the low power testing stuff went wrong. I mounted the 5V voltage regulator the wrong way around, causing the full 15V of the 15V regulator to unleash its fury on my HCT chips. They did not survive and smoke got out. Electronics work on smoke, once it gets out it's broken, so I just went on with the rest of the build. Something to put in the manual: Test the voltages before putting in the IC's, that's basic electronics right there, and even I got tricked by the manual saying otherwise. I also had problems with the green LEDs in both the main board and the interrupter. The green LEDs are manufactured backwards. Check if the cathode (the big dish) inside the LED is on the negative side, that should do it.

Building the rest wasn't hard, but I think the primary coil could have a more nifty way of applying it to the acrylic cylinder. Trying to wrap it around with the clips in place and everything moving all over the place isn't really my thing. I'm thinking of designing something better, but also for tuning the primary circuit better somehow, by varying the coil turn amount.

When I got my replacement chips I could proceed with testing the GDT. By the way, the normal LS versions do not work. At first my local supplier only had these so I tried them anyway. The GDT buzzed happily so the next test up was the IEC power test, which it passed. Another thing for the manual: during the high power test, do not touch the top of both capacitors to feel if they're hot. The manual states to check if those get hot, in case of reverse polarity. Unfortunately, there was in my case 150VDC between the tops of those caps. Was a nasty surprise, but I'm probably used to it.

Startup problems
After the tests the only thing I could do was proceed with the full test: applying power and starting the thing. I did this outside, with a counterpoise of aluminum foil underneath the coil, on a table. The coil and counterpoise were grounded to a port under the attic. I was under the carport, but it was a rainy day, so the humidity must have been high. The resistance from top to ground was measured at all times.

When turning on, buzzing was heared, but no sparks seen. I've turned it up until 1/3 power, and the buzzing got louder, but no sparks. After that, I tried more grounding by connecting everything to a metal pin in the ground, but that did not improve the thing further. I detached the topload, and it turns out that my coil was arcing on the inside. After this, the GDT also stopped buzzing, so I figured that the gate drivers also must've died

Image

I've moved the wire in the photo, but before the arcing it was vertically down from the nut in a little loop. I eventually fixed it by doing a few simple stuffs. First of all, I let the wire run on the outside of the coil to the topload. I used lot's of hot glue to isolate the exposed nut on the inside of the coil. My best guess is that this at least prevents the arc form entering the inside of the coil. I also ordered some more silicon.

Working coil
So yesterday, With a complete package of IC's, gate drivers, IGBT's and a lower value tank capacitor. I tried testing again. This time inside.

Image

With this setup I went for testing. One tesla coil standing on my counterpoise of aluminum foil. The foil is connected to the ground on my IEC cable, and both of those grounds are connecting to a pipe under my sink just on the left. The breakout point was aimed at the foil sticking out the most. When turning on, a little blue/violet spark was visible on the breakout point. Finally output!

Unfortunately that didn't last long. When I was bathing in a nice smell of ozone and pushing beyond 1/3th power, the spark was maybe 5-7cm long, before it suddenly stopped :cry: It still buzzed a little when turning the power knob, but no output. Closer inspection showed that the top half of the bridge was damaged. This IGBT showed no resistance between collector and emitter.

Today I installed the new bridge IGBT's, and also the default 68nF tank capacitor, as I had the suspicion this wouldn't hurt my primary resonance. Throughout this last 2 weeks, while reading this forum, I got more and more convinced that the secondary circuit had a larger frequency than the primary. A post of one of the oneTesla members told that to increase the primary oscillation, a smaller value tank capacitor could be used instead of adding more topload, or decreasing primary windings.

Time for some testing again. I also had a power meter connected to the outlet where the coil was connected to. I am measuring the current draw from the mains, so I can see what happens. This is a pic of it:
Image

When firing up, a tiny spark again. Oh well, output at least:
Image

Turned it up to 1/4th power:
Image

This runs stable, so I've even tried 1/3th power. The sparks are getting so much longer and fatter :D I did not dare to go higher, breaking one bridge is costly enough as it is, let alone the repair work itself turn out to be a pain in the *ss.
Image

Specs and measurements so far

  • Original oneTesla coil
  • 230V edition
  • 47nF tank capacitor, instead of default 68nF cap
  • 6 primary windings, close together
  • Secondary resistance: 221 Ohm


Current draw vs power setting vs spark length:

Coil off:
0%: 0,006A - no sparks (obviously), this seems to be the idle current draw

Coil on:
0%: 0,058A - 1cm tiny sparks and corona visible
25%: 0,207A - 5~7cm sparks
33%: 0,512A - 20+cm sparks
50%: 0,765A - 30+cm sparks
75%: 1,052A - 35+cm sparks
100%: 1,574A - 35+cm sparks

Will try to fill in some more data when I dare to run higher.

The noise level is high! Even at a third of the power I'm not keeping it up for long, because it gets late here. For now I can experiment and try out stuff. I'm waiting for my scope to take some better measurements, because I still feel it's a little out of tune.

All in all, it's a nice kit. I would see some more protection around the IGBT's, as burning them out is expensive, and a hassle to replace. Also, be prepared to spend some more money on replacement parts. I'm happy to have some in stock, in case stuff goes wrong again. I'd like to use this coil as a stepping stone to a bigger tesla coil, with spark gaps and stuff, but first I'd like to tune this to behave well.

Yet a few questions remain here:

- My arc sounds like crackling or popping sometimes, is this normal behavior? Deemed normal, it has something to do with the interrupter coding
- I tried running some MIDI files, but the software seems buggy and freezing. The USB adapter is recognized only half the times, and 1 or 3 seconds in the song, the sounds freeze on the last played tone. I don't know if this is my interrupter, or the software. Fixed, the electric field was disturbing the midi cable
- Does anyone know an acceptable mains draw of this 230V edition when in full power mode? This way I can aim for something. Got it
Last edited by Freebee on Tue Nov 18, 2014 12:25 pm, edited 3 times in total.
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Frost273 » Wed Nov 20, 2013 2:31 am

You're right about finding out if the capacitors are hot. They surprised me too :D

Looking forward for your new posts. Want to know how you'll be tuning your coil with a usb-oscilloscope.
Frost273
Magnificent MOSFET
 
Posts: 152
Joined: Fri Nov 08, 2013 11:29 am
Location: Ukraine

Re: I did it, working coil! (and datalog)

Postby DJKOR » Thu Nov 21, 2013 11:29 am

Nice work. Unfortunate to hear about the blown components but it's a story that we all keep hearing about.

Just a few responses:

Freebee wrote:Electronics work on smoke, once it gets out it's broken...


As my teacher in college always said "don't let the smoke out".

... and even I got tricked by the manual saying otherwise.


I'm not one to RTFM, but I did look through the entire thing before building and did see this on page 19 which covers the basic electronic theory:

Image

They probably should have put it in the construction section, but I guess this was the most logical location.

Trying to wrap it around with the clips in place and everything moving all over the place isn't really my thing.


You can actually place the clips on after you wind the coil. This is why it is stated in the manual that they can bend a little to allow this but you just have to be careful.

Current draw vs power setting vs spark length:

Coil off:
0%: 0,006A - no sparks (obviously), this seems to be the idle current draw

Coil on:
0%: 0,058A - 1cm tiny sparks and corona visible
25%: 0,207A - 5~7cm sparks
33%: 0,512A - 20+cm sparks

....

- Does anyone know an acceptable mains draw of this 230V edition when in full power mode? This way I can aim for something.


I'm curious as to the accuracy of your current meter. Your power consumption does seem a little low however I'm not saying it's incorrect. My data isn't exactly the best either as my configuration is different, but I have some values here: viewtopic.php?f=24&t=1068

- My arc sounds like crackling or popping sometimes, is this normal behavior?


This behaviour is normal and others have mentioned this observation too. We still have not found out what is causing it though.
Image
My build thread: viewtopic.php?f=15&t=998 | 246kHz Primary / 267kHz Secondary
User avatar
DJKOR
Magnificent MOSFET
 
Posts: 193
Joined: Sat Aug 17, 2013 4:12 am
Location: Brisbane, QLD

Re: I did it, working coil! (and datalog)

Postby Freebee » Thu Nov 21, 2013 8:36 pm

I was actually talking about the insert chips, the should be left out prior to applying power to the system, then measure the supply voltages. The manual states to insert them, so I did. The fact I made a mistake by reversing the regulator was my mistake :D

I should see about the current meter. Keep in mind I use a 220v version, and also a lower value tank capacitor as bailey suggested. I still have no idea about the oscillation frequencies i'm running at, but they should he closer as with the old tank cap, thus bringing current consumption down a bit. I might feel confident this weekend and test with higher power settings. :roll:
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Freebee » Mon Nov 25, 2013 6:30 am

I've gotten music to run!

See this thread. I've had lots of troubles with the electric field created by the coil, causing my signals to latch up and interfere with the song and usb port.

Moving further away seems to have solved most of it.
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Freebee » Mon Nov 25, 2013 3:07 pm

I've just turned up the coil to maximum :twisted: , and I have some nice data to work with, even without scope.

I've completed my amp draw from mains with this setup.

0%: 0,058A - 1cm tiny sparks and corona visible
25%: 0,207A - 5~7cm sparks
33%: 0,512A - 20+cm sparks
50%: 0,765A - 30+cm sparks
75%: 1,052A - 35+cm sparks
100%: 1,574A - 35+cm spark

This is with a 47nF tank capacitor in the primary, the original 6 windings, and a 220 Ohm secondary coil.
I noted that after 50% power, not much more spark length was added, maybe a little more massive, but not impressive improvements. The pictures doesn't do credits, phone camera and lighting I'm afraid.

Image

Moved the breakout point a little.
Image

I've wound a second coil with 5 windings of 2,5mm^2 massive wire. These windings were spread out a bit.
The performance of this coil was bad, resulting in over 1,2A amps draw from the main, and a pretty weak spark (maybe 10-15cm) at 50% power. I stopped there as I'm being very careful now.

The somewhat depressing self-wound primary coil.
Image

My guess is that with the 47nF tank capacitor, my primary resonance frequency is already pretty much in tune, and shifts out of tune with the secondary when the sparks get longer. I think I'll be able to try 6 primary windings spread out, or even 6,5 windings on the primary, see where that gets me. Without a scope here yet I can only guess, but at least I feel I make good guesses, and I can run at full power without blowing stuff up.

I'll need to try the coil in a better area, with lots of flat ground, so I'll have to be outside for that. That might change lots of stuff too, and I can always improve the grounding. For now, the only thing providing ground is a small counterpoise, and a connection to the water piping. The rest is all bad.

I've also tried running without breakout point, resulting in a few minor flashovers at the secondary coil. I stopped after that, I don't want sparks to break out where I don't want it.
Last edited by Freebee on Tue Dec 03, 2013 3:59 pm, edited 1 time in total.
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Freebee » Tue Nov 26, 2013 4:57 pm

Tested a new primary coil, this time 6 windings spread out, also with 2,5mm^2 massive wire. It performed worse, drawing over 2 amps from the mains barely at 50% output. I guess my current setup is still pretty much in tune, yet again, I can't say much about it without a scope.

Fried the 15V regulator somehow, I left it on for a while, and then noticed only the red LED working. Replugged the laptop charger, and the blue led worked, but only for a while, then the 15V regulator started smoking. It gets hot now instantly, and when I plug in the power, both LED flash due to the regulator shutting down and starting up to prevent damage.

It worked fine 10 minutes before. Maybe it was already damaged from shorting it out when I failed to insert the 5V regulator during the building and testing phase.

And... whaddayaknow I got every chip in stock now, except the regulators... :roll:
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Freebee » Mon Dec 02, 2013 2:52 pm

Well, I got the low power voltage problem fixed. It wasn't easy, as it had cost me 2 more regulators. I continuously had gotten problems with the 15V part. No gate regulator IC's in, no fan in, and somehow there was 5 to 8V present where 15 should have been. I've measured and probed, checked my soldering over and over, but in the end I had two 15V regulators that were bad from the start. Weird, I guess there still is something that went over my head. I guess I already damaged the 5V regulator a little by reversing it in the first place (during early assembly), so I replaced that one too.

Both regulators have little heat sinks now, guess that won't hurt performance either.

When doing some songs and playing around with it, I noticed something weird with the grounding. This is the setup as I've previously used, here the coil functions normally, with the aforementioned mains current draw, and sparks big enough for my liking. It's not running hot, sparks could still be better, but without further tuning I'll keep my hands off that. The output is reasonable stable, a bit of crackling at lowest power, sometimes a bigger spark here and there.

Image

In the next setup, I've disconnected the counterpoise, and only an external ground from the water pipe behind it was used. The sparks in this setup are less stable, as in more frequent longer sparks between the output. I can only guess that this is due to the counterpoise not being directly underneath it, so the coil cannot discharge that easily, and the output is bigger. After increasing the power some more, I seemed to have triggered the GFCI. I did not noticed, because the GFCI probably isn't behind my group (ungrounded second floor), yet somehow I triggered it. Also the current draw was increased significantly, up to 2 amps at 50% power, but an increase in arc length.

Image

Then I tried disconnecting the ground entirely. The counterpoise was disconnected, and I also disconnected the wire from the water pipe. I only left the coil on lower power settings. Output was present however. About the same, and maybe even 'better' performance as with the counterpoise removed, but more amps draw and lots of distortion on nearby electronics, which is normal, but also not good.

Image

In my case, the second setup seemed the way to go, but unfortunately it triggers a ground fault interrupter, which doesn't affect me, but I don't want it none the less. I guess it's high time I take it outside and try it with a metal pin in the ground. That way I don't have to worry about GFCI's, and it would also make everything else around it better grounded than the piping in house.

Here a few obligatory pictures from when I tried drawing arcs with a strike target.

Image

Image
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Freebee » Wed Dec 04, 2013 3:47 pm

I just tried adding more windings on the primary coil. Still waiting for my scope, I saw it has shipped, but... China :roll: I'm flying blind here, I can only vary my windings and check the results in spark length and mains amp draw. I've gone from the original setup posted in the OP here, and changed only the primary windings.

At first I tried 6,5 windings. I've stepped off the huge spreading shown in the previous picture, and instead tried adding half windings.

  • 230V edition
  • 47nF tank capacitor, instead of default 68nF cap
  • 6,5 primary windings, close together
  • Secondary resistance: 221 Ohm
  • Primary diameter: barely 7cm

I got more amp draw from mains, up to 1.9A at 100%. Sparks were about as big as with 6 windings. The sparks stopped growing at about 50% power, only to become a little fatter, but not really much. Seems awfully familiar with my original 6 windings. Probably due to the fact that my diameter has also changed to a smaller size.

Then I went for 7 windings.

  • 230V edition
  • 47nF tank capacitor, instead of default 68nF cap
  • 7 primary windings, close together
  • Secondary resistance: 221 Ohm
  • Primary diameter: barely 7cm

This actually made a noticeable change. Amp draw was larger, but so where the sparks. I think I got the 30cm sparks at 33% power. At 40% they grew even more, but I had to stop there, as the secondary was arcing over to the primary. I think this is actually due to the fact I used a smaller diameter, where the secondary coil is way too close to the primary, and also I used black duct tape, which may contain carbon(?). I used a cardboard tube at first, but that arced over like hell, so I slid a piece of brown PVC over it, which may also contain traces of carbon.

I also probably need to give it a nicer coating of varnish, as the current coating does not hold.

Here's a picture showing the setup.
Image

Also I can totally advise for using sandpaper to sand the toroid while putting it on a spinning drill. Just look at the awesomeness it adds!
Image

I am definitely going to experiment more with more windings. I might buy some length of (non-dark) 80mm or 90mm PVC tube, and make a better primary from that, as the current setup seems holding it back. Also, what would the primary diameter have for effect? More coupling?
Freebee
Terrific Tube
 
Posts: 50
Joined: Sat Nov 02, 2013 2:27 pm

Re: I did it, working coil! (and datalog)

Postby Speedy78 » Wed Dec 04, 2013 6:01 pm

More windings, more coupling. The secondary to primary strikes are probably due to too high of a coupling factor. You may be able to move the whole bundle down some on the primary former to reduce the coupling factor. I would start deviating too far from the 6 windings until you scope it and see what youre tuning mismatch is.
Speedy78
Magnificent MOSFET
 
Posts: 127
Joined: Sun Oct 20, 2013 3:26 pm

Next

Return to Completed oneTesla Kits

Who is online

Users browsing this forum: No registered users and 20 guests


cron