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Magnifer & rotary problems



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From:  Richard Hull [SMTP:rhull-at-richmond.infi-dot-net]
Sent:  Thursday, June 18, 1998 10:33 PM
To:  Tesla List
Subject:  Re: Magnifer & rotary problems



Tesla List wrote:

> ----------
> From:  pacster-at-ibm-dot-net [SMTP:pacster-at-ibm-dot-net]
> Sent:  Wednesday, June 17, 1998 4:39 AM
> To:  tesla-at-pupman-dot-com
> Subject:  Magnifer & rotary problems
>
> snip



> When I was finally brave enough to put the stationary electrodes in position
> (backwards at the moment just in case the rotor turns to dust) I connected
> the rotary up to the primary circuit. The rotary is driven by a servo motor
> with a home made solid state control circuit and a 5amp fuse. As soon as I
> applied power to the primary circuit the servo motor began to change speed
> sporadically, as I increased the neon input voltage to 100V the motor popped
> the fuse, I thought it was odd and so replaced it with a 10 amp fuse and
> reapplied power. At about 100V the controller died, I replaced the broken
> diode and I haven't run it since as I am confused as to why the motor would
> hunt when the primary circuit was energised. I made sure that there was at
> least 2" of clearance between all HV points and the motor housing and frame.
> Is it possible that the high E.M. field given off by the secondary and
> tertiary coils is inducing voltage spikes in the wiring running between the
> motor and the control circuit? If this is the case should I get shielded
> cable instead of normal 3 core wire and shield the control circuit, and then
> connect the shield to mains earth or the RF ground?
>
> After all these problems I removed the rotary and just used a variable
> copper multigap (42 1.5" dia. tubes in series). When the neon input voltage
> went above 80V  the secondary terminal would arc to the primary coil which
> was around 15" of white hot spark and there would be just a few weak
> streamers off the tertiary coil. At present the toris on the secondary coil
> has a 4" cross section and a mean dia. equal to that of the secondary coil.
> Should I increase the tube dia. for a higher brake out  voltage or would it
> be better to increase the insulation between the primary and the secondary?
> At the moment there is around 1/2" of  polyethelene between the primary and
> secondary coils but none between the torrid and the primary.
>
> If I should increase the secondary torrid diameter will this decrease
> performance or have no affect? One thing which has been confusing me for a
> while now  is how does performance change if the primary and tertiary
> circuits have a constant L/C ratio and the secondary L/C ratio is varied up
> and down?
>
> Thanks heaps for your help and time.
>
> Mark B.

  Mark,

The use of any low level logic or semiconductor motor controllers for rotary
motors is a study in disaster.  The EM field in the area of same are often in
the millions of volts per meter!  Only good old hard wired high current low
voltage lines with low impedance to ground stand any chance of long term
survivial in rotary motor circuits.  The servo is elegant and great until you
start doing sparks or you gap fires sending the huge E Fields out screwing with
all those lovely 5 volt logic lines.  Shielding is possible I suppose, but would
be a lot of effort for small or temporary rewards.

The use of larger toroids or terminal capacitances may or may not help based on
a lot of design criteria which experience teaches.  To get experience you just
cut and try.  This list and myself have posted many, many times on some of these
criteria.  The bottom line is try it.  But be prepared to change tune, add more
power, etc.

Richard Hull, TCBOR