isolation transformers & Ion Motors

• To: mail11:; (-at-teslatech)
• Subject: isolation transformers & Ion Motors
• From: pierson-at-gone.enet.dec-dot-com
• Date: Tue, 11 Feb 97 18:31:57 EST
• Cc: pierson-at-gone.enet.dec-dot-com
• Subscriber: pierson-at-gone.enet.dec-dot-com Tue Feb 11 23:09:11 1997

1) a non tesla ion motor:

We had an ESD tester with a roughly 8" AL sphere and a discharge
point electrode epoxied on.  I bent up about 12" of Cu wire,
hammered a flat in the middle, and center punched it.  This,
balanced on the discharge point, spun, slowly, at 18KVDC, nominal.
No visible corona.  It does not take extreme voltage to run one.

2) Isolation transformers...
These come in lotsa different types.  MOST are NOT good for stopping
conducted EMI.  The common ones allow fairly massive (at RF freqs) coupling
from primary to secondary by stray capacitance, between the windings.

A few, expensive when new, separate the windings, and add a grounded
shield between, so that the 'only' coupling is via the flux in the core.
These can be fairly effective, tho see below.  Either may work, for
emi suppression, but the first is iffy.

ANY device 'in line' is at risk of the emi simply 'radiating around'.  If
the filter is simply plunked into the middle of the line, EMI can radiate
by it an couple in on the other side.  For optimum effectiveness, the device
needs to be 'in the wall' of a faraday cage.  (again, they may help, even if
not so installed...).  In general, devices want to be either 'at the source'
so as to reduce the amount of wire carrying noise, or at the place where
the wires leave the area.  Both doesn't hurt.

	regards
	dwp

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