Rotary Spark GapsThe Concept:
The gap is designed with 2 sets of stationary gaps, and 4 rotary electrodes, on each rotation a pair of rotary electrodes 'make' with each of the stationary electrodes, then the other pair of rotary ellectrodes 'make' with the stationary electrodes in turn.
This means that although there are 4 rotary electrodes, a complete rotation yields 8 'breaks'.
Another advantage may be that an arc is forced to break once it gets close enough to the next electrodes
Here is the video explaining the concept.
I only have a 11KV 18mA OBIT, which was already in a box, I decided that as the rotary gap was always going to be connected to the OBIT while in use, that I would install the rotary on top of the OBIT box, OK so this meant rebuilding the rotary support etc, but it's a far nicer result.
Controlling the speed of the rotary was the next step, I have an 8Amp variac, which I wanted to make multifunctional, not only would it control the speed, but also be a switch to turn on the OBIT, this meant all manner of connections, namely a couple of 13Amp sockets so i can just plug things in, then a way to connect the rotary/obit with an umbillical.
In my collection I had several multipin connectors (12way), looking up the specs they are rated at 900v@5A, which is ideal for my purpose, then because i had all those pins, I decided to add a couple of auxilliary switches.
Next problem was housing all of that, without modifying the variac with a bunch of holes, the obvious answer was to build a plinth for it to sit on, on the back was the 2 sockets, the 12 way connector, and an IEC connector, the front sloping panel houses a variac power switch, a fixed power switch, and the 2 smaller auxilliary switches.
I also added a handle, because carrying a variac has always been awkward with one hand.
Simple, 2 strings of 15, and a box made of some sort of plastic, with a couple of bolt terminals
I decided that if i'm going to do this right, I was going to build a new coil, Making the supports for the primary was always a problem, so I solved it with a jig that cuts slots at equal distances along the length, and of course there's a video for that here: (this is a more recent video)
The jig was made to bolt onto my router table, it has a location peg that sets where you start the first notch, then sets the spacing, i was able to make all four supports in a matter of minutes, once they were fixed to the base, it was an easy matter to lay the pipe in the notches, then I fixed some bars on top to hold it in place.
As yet I need to wind a new secondary, but testing will be done with a smaller secondary Here is the initial testing with just the primary connected:
Video of test with temporary secondary
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