I'm looking for a way to check if some devices have power. There are solutions like cheap 5V wall warts, relays, neon glow lamp... But from my point of view the power waste is to big. Also relays have the problem that most of them are not build for high and low voltage switching. It would be easy to use a double switching relay if not both switches would be AgSnO2.
But there is another problem i have. I use this dimmers in my house for LED lamps: http://www.eltako.com/fileadmin/downloads/en/datasheets/B_datasheet_EUD12NPN.pdf And i want to check if they are on or off.
I found this circuit that wastes just 120mW: http://www.dextrel.net/diyzerocrosser.htm Is this an option to detect power? And will it work behind my dimmers?