Looking through my "stuff" and found these items I have had for ages. One is a (Brown converter for continuous balance system) The other a (S.P.D.T. synchronous converter switched by 19 volt AC) What and how were they used? WW2 stuff so only you oldies may be able to help. Pictures on alt.binaries.pictures.radio Warren
Part of a Honeywell-Brown autobalance potentiometric chart recorder. Chops the error voltage at line frequency. This is then amplified and phase split and used to drive a two-phase motor which drives a slidewire potentiometer to restore balance, and the pen/pointer assembly. Used extensively in steelworks and power stations well into the 1970s.
Pics not available here, but it sounds like another synchronous chopper as described above. Maybe Leeds & Northrup.
-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more
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