due to variation of make-to-break ratio of intermittently-operating contacts, e.g. using Tirrill regulator

Full Title

Circuit arrangements for charging or discharging batteries or for supplying loads from batteries > for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle > Regulation of the charging current or voltage by variation of field > due to variation of make-to-break ratio of intermittently-operating contacts, e.g. using Tirrill regulator