Re: rotary gap electrodes

>From: "William L. Osburn" <wosburn-at-utk.edu>
>To: tesla-at-pupman-dot-com
>Subject: Re: rotary gap electrodes
>Jim =
>>There are NO heat sinks or forced air cooling on this rotary. The only
>>air flow is that generated by the moving points. It is enough to even
>>cool the 4 stationary electrodes.
>4 electrodes?  How is it built? Please describe.
>*** Magic Bill ***

                            O /------|
                         O     O     |
                in -|-> O   o   O <--|-- out
                    |    O     O
                    |-----/ O

	I have 8 electrodes mounted on a phenol disk. All of these
rotary electrodes (Os in the diagram) are shorted together with a
metal ring. The 4 stationary electrodes ( > / \ < in the diagram) are
facing the rotary electrodes with about 0.030" of gap between their

Notice that the > and / or ( / and < ) electrodes are 1.5 gaps apart.
In my diagram, the > and < electrodes are commutating, if the rotor is
rotated 22.5 degrees (360/8/2) then the / and / electrodes will

This feature gives me twice as many commutations per rotation as a
single set of stators would.  It does have the disadvantage of
throwing completely circular power arcs under poor match conditions
though. This circle of fire is a sight to behold. I'm not sure if it's
a disadvantage;) Additionally, since I build this rotary gap, I've
measured it up to 7000 RPM, so I do not really need the extra
commutations per rotation. When I build it, I did not know how fast
the motor that I had would rotate.