Tranformer efficency VS Frequency

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Alexander Rice by way of Terry Fritz <twftesla-at-qwest-dot-net>" <alex-at-rices.myip-dot-org>

Hi All
		We did an eperiment in physics today which investigated the effects of 
operating frequency on the efficiency of an ordinary laminated core
transformer.
	Using a power sign gen we input current at varying frequency into the 
transformer, power in and power out was calculated from the product of
Current and 
Voltage at each side using ordinary multimeters (not true rms ones)
frquency was 
varied from 2Hz to 2Khz.

	Heres the rub, i was expecting to see an increase in effiency as frequency 
increased, bearing in mind the way switched mode power supplies work, what
we actually 
found was that effiency peaked sharply at almost exactly 50Hz and dropped
off sharply 
either side - which puzzled me. My theories are - transformers really do
this, maybee 
it is somehting to do with the thickness of the laminations and induced
eddy currents 
OR our meters are at fault - DOES ANYONE HAVE A BETTER EXPLAINATION?

This does have a relevance to tesla coils - wouldnt it be great not to have
to lug a 
great hunk of iron and copper when you want to run your coil - maybee we
can harness 
the SMPSU's out of the newer breed of microwaves - maybeee this will be the
'next big 
thing' in coiling

a mildly confused

Alex