Tuesday, October 11, 2011

even yet more further additional progress on my "Last Tesla Coil", book two, part twelve, chapter 27...

laceration engine.jpg

You might think this is the nearly-finished primary of a Tesla coil. And you would be reasonable to think so. But you would be mistaken. This is a laceration engine.

Well, I couldn't wear gloves because I needed the dexterity and the clearance between turns. I tried. I tried rubber gloves, but they didn't protect, just as I'd expected.

After I get done putting Band-Aids™ on all my fingertips, I'll have one more go at straightening and evening-up the turns, leaving them a bit tighter (to keep them from shifting -- as much), which is to say less of a perfect spiral, and more of an octagon. Then I will cut the outer end to its final length and screw it down. Wee! All this should be done a few hours after this post goes up.

It will be badly tempting to lash up a primary circuit for it just so I can try it out, but although I have most of the parts, nothing is put together. Also, I don't have quite enough capacitance, methinks. Gotta go through the calcs one more time after I measure the as-built primary inductance and plug it into the formulae. Furthermore, the HV transformer for this coil is practically unreplaceable, and I'll be damned if I will blow it up, which means I really need to finish the "Terry Filter" for it before running it. *sigh* Did I ever mention this? This coil will be fed by DC, so no resonant charging. I wish to be very kind to my precious 120mA NST, and I am effectively isolating it from the primary circuit entirely.

I wish there was a way to make that primary stay this pretty pink color forever, but there isn't. If I spray it with acrylic now, the acrylic will get all over the finished wood and mess up its finish. It wasn't practical to spray it before installing it - I thought about it for all of ten seconds. There's over 90 feet of 1" copper strip here, so I'm not gonna be dabbing Futura on it with a cotton swab, or laying it out on the sidewalk to spray it.

I'll spray or coat (Futura floor wax also works great) all the brass. That'll have to be enough shiny. The copper will all be dull brown in ten years.

I'll take a "glamor shot" of the complete Tesla coil primary and secondary -- minus one minor dodge I have to add to the strike rail -- later tonight.

Okay, it's later: MLTC milestone.jpg

Inquiring minds will want to know what else needs to be finished before it runs. Here's a laundry list:

* primary capacitor - this will be an MMC of course, the most reliable sort there is. I have most of the caps for this, bought as a "finished" (bleh) MMC, but I am not comfortable with the number of caps in each string (determines the maximum safe operating voltage of the complete array) so I will need to add a cap or two to each string. Since that lowers the capacitance of each string I'll need to buy enough additional caps to add another string or two as well. The cap will be built with brass "strapping" terminals mounted on the exterior so that any number of strings may be placed in or out of circuit.

* spark gaps - I have one spark gap completed, but intend to build at least two more. The finished one is the "sucker gap" previously about posted here. I've got a disk, hub, and shaft done for an asynchronous rotary. I've got all the electrodes made, but not yet drilled, for a Richard Quick style gap. I've made nothing else nor thought about the housing for that. I'd kinda like to make a gap like one that Old Nik' was known to have used in his original NYC lab before it burned to the ground. It was just a bunch of brass balls in series. Not the best performing gap, but if memory serves, that was long before he'd invented several new kinds of fast-quenching gap switches.

* control panel - again, I've got most of the expensive parts for this, but there's a lot of finicky work to be done on said parts. I'll need to make new cards for the meters. I'll need to obtain a few specialty parts like a current transformer. The HV transformer is HEAVY so I'm considering building a cart for the control panel rack cabinet (which will be heavy enough without the transformer in it) and possibly putting the transformer in the cart/base. I might leave it in the panel cabinet and use the cart/base for storage of cables and parts. I haven't thought very much about that. And there's surely a ton of small parts I don't have, like controls. Much work to be done there.

* the damned primary tap connectors. These are gonna be finicky to make, but a joy to have and use versus any other primary tap method I've ever seen used by anyone, anywhere. So there. Okay look, that crazy rotating thing with the sliding brushes doesn't count - that's not "tapping". Yeah. So anyway, I think I've got the design worked out. I haven't started collecting various red metals (copper, brass, bronze) yet. And I have to make two of them. Bleh.

* cabling & miscellanea - the ground connections, a ground rod kit with straps, the umbilical between control panel and coil, to name a few examples.

So there is still a long, long way to go before we see first light on this beast.

PS: I noticed just now that pictures in some of my older posts are missing. I'll look into this in a bit. Probably nobody but me noticed anyway.

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