Monday, February 20, 2017

Creating Lichtenberg Figures with Microwave Oven Transformers

Obligatory Safety Warning:

     This is not comprehensive instructions on how to build one of these devices.  Please do not attempt this if you do not fully understand the concepts that you are working with, and even then, if you are not incredibly safety conscious this can easily kill you.  I have seen many videos on the internet of people doing this in a very unsafe manner.  Please do not emulate these videos.  This setup creates the potential of 4000 volts, which will jump an air gap.  This means that you do not have to actually touch this in order for it to kill you.  One little mistake can easily be lethal.  If you do undertake this project, always have a second person present to call 911 in case you only mortally wound yourself instead of killing yourself instantly.

      Now that I have absolved myself of the liability for anyone's death or injury, I'd like to assure my family and friends that I am doing this in an incredibly safe manner, and there is no need to be concerned for my safety.  Now, on to the fun.

Above are the two microwaves I will be disassembling.  If you ever decide to remove the outer housing from a microwave for any reason, please pay careful attention to the warning in the picture.  You can  verify that the caps are discharged by shorting the terminals with an insulated screwdriver.

 Look at all the neat stuff I was able to pull out of these two microwaves.  Only the transformers will be used in this project, but I'm sure the rest will come in handy in the future.

Above is the final project.  Not really that much to it.  The light bulb is just a safety precaution to remind me when it is powered up and dangerous.  Credit to the following website for the wiring schematic using two transformers for a total of 4000 volts:

Now for the real test.  For my first attempt I grabbed a scrap piece of red oak off the top of the wood pile.  I thought oak would absorb the electrolyte mixture better than other hardwoods due to it's porousness, but I was wrong.  Even with the electrodes just 4 inches apart nothing happened other than a little popping and crackling.  It seems that the rapidly produced heat evaporated the water leaving a dry patch around the electrodes, which prevented the current from going anywhere.  Next I tried poplar, thinking it might absorb the mixture a little better, but the results were the same.  I started to get discouraged, but I wasn't ready to give up yet.  A pine 2x4 led to the first success, although it wasn't very impressive.  In addition to a lack-luster pattern, as soon as the carbon trails got too close to each other the current arced through the air, and the dead short blew the fuse I had added as a safety precaution.  Luckily two microwaves equals two fuses, so on to the next trial attempt.  I used a small scrap piece of plywood because I had read that it would absorb the liquid into the first layer of laminate, but the glue made a water proof barrier to keep the mixture from soaking all the way down through the wood.  Sure enough, it worked much better than my previous attempts (video below):

A quick note on safety, there is a white isolation pad between the experiment and the table.  This is important since 4000 volts will jump through materials typically thought of as insulators in search of ground, so you can never have too much insulation.  In addition, all wiring on the secondary side of the circuit is rated for high voltage.  Typical electrical wire is rated for a maximum of 600V.  If you were to use anything other than wire rated for high voltage, such as is done on many internet videos, then you must treat the wire like it is bare copper.  It is an unnecessary risk.  Tangent over, let's move on.

Here is what it looked like after I scrubbed off the excess soot:

Not bad, but I think it would have turned out better if it had continued burning for longer.  Unfortunately it stopped when it did because it arced and blew my second and last 20amp/120V fuse.  I realized that if I continued in this manner I would go though quite a few fuses, and my Lichtenberg figures would all stop before reaching their full potential.  The fuse was my idea anyway, and I only used it because I harvested the fuse and fuse holder from the microwaves, so I thought "why not."  Now that I know why not, I decided to bypass it using the old "penny in the fuse box" trick.

That should do it.  If my new "fuse" blows than I have bigger problems than replacing it.  And I'm still protected by the 20 amp breaker for that circuit, so really this is not as unsafe as it might seem.

Here are a couple more videos using different types and thicknesses of plywood:

Here are the results from several more attempts using plywood:

I thought these turned out OK. but I still wasn't satisfied.  They burned too deep, and lacked the detail that I had seen when researching other people's Lichtenberg Figures, so I decided to try something else.  This time I used MDF, and it worked much better.  The designs are much more detailed and more like what I was looking for.  I didn't take any video of the MDF, but there was a lot less fire than there was with previous woods.  Here are the results:

Not bad for my first time.  When I first started this project I thought it would be something that I would mess around with for a weekend, and then put it on a shelf to gather dust with the rest of my short-lived interests, but I think I might do a little more experimenting with this before it gets retired.  All of the figures above were done by saturating the entire surface with electrolyte and using two fixed positions for the electrodes.  I think I might try some bigger ones where I only paint part of the surface with electrolyte in order to influence the flow of the current.  I might also try moving the electrodes around to different spots on the same piece.  We shall see.  If I never do another post on this subject it probably means that my attention was pulled in a different direction, and my fancy new Lichtenberg Figure machine has been retired to the shelf after all.

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