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Herald1360 · 9th Nov 2019, 1:18 am

"Mains energised" has always struck me as rather a misleading term- the field coil has to be energised with dc, direct mains would be useless! You can get away with a fair amount of ripple voltage since the high inductance of the field coil means that the actual ripple current in the winding is quite low.

9th Nov 2019, 1:18 am	#23
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: 1930s field speaker? "Mains energised" has always struck me as rather a misleading term- the field coil has to be energised with dc, direct mains would be useless! You can get away with a fair amount of ripple voltage since the high inductance of the field coil means that the actual ripple current in the winding is quite low. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O