Kemo M103N Master / Slave Switch 230V/AC (400V/AC) Switches off other load when machine is turned on, lamp etc. Monitoring of 1-phase or 3-phase machines, Black : Amazon.de: DIY & Tools
Current Sensing Slave Power Switch
EP0315366A2 - A regulated dc power supply having master and slave regulators - Google Patents
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Circuit Labs - Electronic Circuits Collection: Mains Slave Switcher II