It's a nice looking coil Bud. The second secondary has a more matte look to it - does it have any poly/epoxy coating on it?
Udo gave a very good explanation of what you might be seeing. In a DR coil you have explicit control of so many factors, so if you are trying things out and notice a change in spark length/strength it is helpful to keep track of how you have things set. A particular burst length or BPM might not be able to take advantage of a particular coil - or a current limit might not let a coil take advantage of the burst length you have tried to choose. But if a setup has been optimally tuned and its producing smaller sparks than you expect, you are probably drawing less power than you expect. If your cap can handle the higher voltage then you can set a longer pulse length from your interrupter to bring up your primary current with the small cap and you may see bigger sparks. If you have a set pulse length and BPM, then using a smaller primary cap and longer primary coil is going to give you reduced performance simply due to lower power throughput. You can't just increase primary capacitance to an arbitrarily high value though to get more throughput, because you will run into problems maintaining tuning as your primary gets short - you won't even have a full turn at some point. You will also get high currents that quickly overwhelm your bridge silicon without current limiting - and if you do have current limiting, the current limiter will not allow you to maintain the set pulse length.
From: Buds mohrstamping mail <bud@xxxxxxxxxxxxxxxx>
To: Thomas Shurtz <whompin105@xxxxxxxxx>; Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tuesday, May 31, 2016 8:43 AM
Subject: Re: [TCML] solid state tesla coil question
Thomas, Here is a link to the minibrute pics in my photo library. In the
photos you can see the two different secondary's used.
http://s1243.photobucket.com/user/ForrestMohrman/slideshow/tesla%20coil/minibrute
Bud
Forrest Mohrman
Engineer
bud@xxxxxxxxxxxxxxxx || 440.647.4316
www.mohrstamping.com
-----Original Message-----
From: Thomas Shurtz via Tesla
Sent: Friday, May 27, 2016 1:50 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] solid state tesla coil question
From what you have said, it sounds like the only constant in your comparison
was the bridge. That's kind of like asking why one coil using a particular
spark gap produces weak sparks , when a different coil can produce strong
sparks using the same spark gap.
We would need more details of the other components as well as an explanation
of how you determined "for sure" that both setups were ideally tuned before
guesses could start to become useful analysis or diagnostic test
suggestions.
There is a thread on 4hv dealing with low impedance vs high impedance DRs.
A low impedance setup will typically have a much larger primary cap than a
similarly sized high impedance primary - and then the secondary can also be
high/low impedance. Multiple coilers have successfully demonstrated either
approach - spark length is still primarily determined by input power for a
well designed and built coil.
From: Buds mohrstamping mail <bud@xxxxxxxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Friday, May 27, 2016 11:50 AM
Subject: [TCML] solid state tesla coil question
I recently finished the minibrute tesla coil and have it running well. The
question is why does this coil operate better with a large primary capacitor
size of .21uf vs. a smaller cap size of say .005uf. I have tried this setup
two different ways by using two different secondaries and at .005uf the arcs
are very weak and small. At .21uf the arcs are bold and long. I know for
sure that the primary and secondary were in tune on both setups.
Bud mohrman
Forrest Mohrman
Engineer
bud@xxxxxxxxxxxxxxxx || 440.647.4316
www.mohrstamping.com
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