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Monday 24 October 2011

My 40kV Uncle Fester impression

With my SIDAC driver and a light bulb, I thought I'd try my hand at doing an Uncle Fester impression. Remember him from the Addams Family?

I'm putting about 40kV out of the ignition coil, enough to spark around the globe. What might not be so obvious is the little ground wire hanging off the globe's base. I'm not actually conducting the electricity myself!

Needless to say, this was done with a full understanding of the dangers of HV and the particulars of this setup.

Plenty of ozone going around, I have to hold my breath for most of it. At some stage I'll actually get a better set of photos, but the vid will do for now. :)

Tuesday 18 October 2011

Transformer heaven

Not far from where I live is a large metal scrapyard. They have a section where motors and transformers go to die, and a lot of what they get is from the local utility + military. Military and utility transformers are highly prized for Tesla coils and other HV experiments, so I really wanted in. My TC really could do with a decent upgrade!

A friendly chat to the workers eventually led me to the owner. This place has a reputation for allowing access to artists (sparks count as "art", surely), so it didn't take long. Access granted! All the blokes there were incredibly friendly and helpful during this.

Of course, my first visit to the place would not have been complete without taking some metal to recycle. So I took some aluminium cans for them, which they particularly appreciated as they'd first have to deal with the beer contained within.

It really is like a toyshop there, except the useful stuff is well hidden. This is what I faced when I went:

I could have spent hours there, but had to be elsewhere so only spent 15 minutes or so. Countless motors there, plus loads of transformers, such as those from microwave ovens, massive utility ones, and a few hefty 3-phase types. But no pole-pig or potential transformers yet (my real desires).

Despite this, I did come away with a beat up old Neon Sign Transformer, which is seen at the bottom of the left photo. And it works it seems! Stay tuned for a quick post on how I tested it "in-heap".

I suspect this will be a regular haunt of mine now, much to the detriment of the girlfriend..

Monday 10 October 2011

GPS feline tracker.

Say hello to Ash. Isn't that a nice collar on him?

Ash is my Russian Blue cat, and loves his neighbourhood adventures. Regularly off for hours on end, he could end up in who knows what garden, possibly halfway down the street. After endless such adventures, I figured it was time to find out where he really was going.

GPS is of course the way to go, so I looked around for a tracker I could attach to him. Turns out that all the ones commercially available are far too large. A common one available on ebay is about the size of a matchbox - too large for a cat. All other pet trackers are made for dogs, it seems.

So it was time to roll my own.

Wednesday 5 October 2011

Rotary encoders, done properly

Rotary encoders, in the most recognisable form, are mechanical devices that look a bit like potentiometers, and are often used in their place. Some audio gear uses them, and are recognisable as volume controls with regular bumps or clicks as they turn. They are also used in mechanical trackballs and mice, as well as lots of other applications that require accurate rotational sensing.

In hobbyist applications, they are handy for all sorts of things - potentiometer replacements, up/down switching, etc. Using them with AVRs, PICs and Arduinos is quite common and they are easily available.

Saturday 1 October 2011

Marx Generator + NST

My Marx Generator gives pretty juicy sparks, but at about 1 every 2-3 seconds from a Flyback
transformer, it's not the most intimidating. Not a lot of power can be gotten from a Flyback (except
perhaps in ZVS mode).

So I hooked it up to a beefier 15kV supply - a Neon Sign Transformer rated at almost a Kilowatt. A
couple of microwave oven diodes rectified the AC into the necessary DC.

Check out the results...