Archive for January, 2009

“The Nature of Light and Colour in the Open Air”

Here is a great book about mirages, solar halos, and other atmospheric phenomena.

Link to Dover Publications

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Why Build a Tesla Coil?

I suppose if you have to ask, you may never understand why so many people build these things. Mastering an elemental force like lightening is not considered, by most, to be a typical hobby. There is obviously a thrill when people see the sparks leap out of the coil and take a few steps back. There is the obvious aspect of danger and the loud sound. It’s probably similar to the  attraction of fireworks.

One key motivation for me, is education. I enjoy demonstrating my Tesla coil and sharing my understanding of it. It is a joy when a teenager asks if they could build one of these. I have assisted a number of young people (with parental supervision) in building their own coils. In the process of building the coil they learn practical aspects of math, physics, materials and the general nature of craft that is required to build just about anything.

On one occasion, working with two teens on their Tesla coil. We calculated the resonance of a secondary coil then after winding it, we tested it with a signal generator and a pair of LED’s. When we found the resonance frequency and the LED’s lit brightly, one of the guys was thrilled at the notion of predicting the frequency! He was hooked and his enthusiasm increased as he worked on the coil. They also realized they had an understanding of the math involved. Wow a practical application of mathematics! Hopefully building a coil might start someone on the track to pursue an education in engineering or science.

Lots of kids are motivated to build things yet they have no sense of crafting an object. For years, we have tried to protect our young people by keeping sharp objects away from them. In our interest of keeping them safe we have reduced their ability to build things to Lego blocks. Lego are sure safe unless you have had the misfortune of stepping on one, bare foot in the dark. Let’s consider that if we let our kids ride a bike or a skateboard, we might consider that we might let them use a few hand tools.

I remember using hand saws, drills, hammers and nails when I was in grammer school. I doubt they allow children to do this any more. I have talked to engineers that did not have occasion to build or construct much of anything before they entered university!

The act of figuring out how to build a kite, a telescope, a toy boat, a model airplane, or a simple electromagnet, or just about anything, can teach a child a huge amount about the way the world works. I believe that knowledge gained this way sticks and comes in handy in what ever field a child might want to follow.

Yes I burned, cut, scraped and bashed a thumb here and there along the way. I can show you some of the scars. Would any of these injuries be a reason to stop a child from following his or her curiosity, their passion? My parents encouraged me in my interests and when it looked like I was getting into something dangerous, dad just payed a bit more attention and dad increased his supervision a bit.

Along this line I can highly recommend the book, Uncle Tungsten: Memories of a Chemical Boyhood by Oliver Sacks. My childhood was not nearly as interesting as his but it rings true. I only wish I had an Uncle Tungsten. I’m sure glad I had my Father who taught me so much, I miss him. My mom was very understanding. That reminds me, I should call her.

Craig

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Time to rebuild

My old coil with a new transformer

My old spark gap coil still works well.  I designed it around a 100ma cold cathode lighting transformer that I lugged around for years before finally building the coil in about 1999. My old website described it in detail. (I’ll add a link here soon.)  About three years ago I made some “improvements” to the coil which resulted in toasting my transformer.  Its a common occurrence to kill the transformer if you don’t have a good filter to block the high frequencies from the tank circuit from getting into the neon transformer.  I had a RC filter which worked great until I beefed up the wire in the tank circuit.

I purchased 6, 4500 volt 410 ma transformers from C&H sales, before they closed up shop.  At someones suggestion (I’ve forgotten the website) I cascaded four of the transformers to obtain 18,000 volts at about 200ma.  I added a Terry Fritz style protection filter. I also built a Jacob’s ladder out of two transformers.  It makes a wicked arc!.  I’ll create a page for the old coil and the Jacob’s ladder real soon. The photo here shows the old coil and the new transformer built into a wheeled cart.(It’s heavy!)

Now its time to build a new coil to match the transformer.  I think I will design it to work well with a set of two transformers.

I’ll show the progress on the new coil here.

Craig

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