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Winding a new - secure - secondary and primary coil

PostPosted: Thu Dec 12, 2013 11:51 pm
by ican
If you have a makerspace in your town - or similar do-it-yourself shop available - you can buy a 2' piece of 2" PVC pipe, 2 x 2" endcaps (they have a black rubber gasket on them and tighten by turning a wingnut on a bolt), and a 4" toilet drain with a metal ring on it (Home Depot PVC aisle.) DON'T hit the PVC ring with a hammer like it says because it will break out the whole center, which you need. The toilet drain without the metal ring isn't tall enough to wind a new primary, and you'll be breaking that metal ring off soon anyway.

Cut the PVC pipe to length so it fits in a lathe, wind 5-10 wrappings by hand with 36AWG magnet wire, and then leave a 1/4" gap and start winding again... start the lathe, and keep the windings tight. If you overlap the winding, go back and keep it tight again. Wind 2000 turns, then another 1/4" gap, and another 5-10 windings to finish off. Hot glue the end wrappings while it is still on the lathe, and then varnish the main section with at least 12 coats of spray varnish, or 4 coats of brush varnish. Drill two 1/16" holes at each end of the pipe right next to each other, and insert a heavier gauge wire through one hole, leaving a loop on the outside of the pipe. Cut the wrappings at the gap on each end, weave your 36AWG through the loop of the thick wire, and solder the wires to each other. Pull the wire tight from the inside of the pipe, and tape it down well inside the end of the pipe. Cut off the ends of the pipe making the secondary 1/4" longer on each end than the holes you drilled previously, which should be about 10.75" total length. Secure the thick wire to the bolt of each endcap. Glue the endcaps on to the pipe, and forget you ever broke a secondary wire in the past. With the Toroid attached, you should see between 450-475ohms of resistance through the secondary, which should be around 240kHz if my memory serves.

Drill a hole through the center of the toilet drain so the bottom bolt of the secondary fits through, and glue the secondary on the inside of the toilet drain. This is your new primary coil form. Wind your 8-turn 10AWG stranded primary tightly around the toilet drain, twisting the ends of your leads together and taping the winding to the form with electrical tape. Secure the entire assembly to the acrylic top of the oneTesla case if you so desire, or just use the wingnut included with the endcap to secure everything together once it is assembled. Test your resonant frequency, and remove primary turns as needed to get within 10% of the secondary resonant frequency.

Pictures of the whole process to follow on Sunday when I build it. This is tried and tested on another oneTesla coil setup, and it throws the longest streamers and is the most stable coil we've seen in our collection of DRSSTCs so far. It hasn't blown an IGBT or Diode since having this coil system wound.