I am considering a new project to turn on an electric water heater on my way home from a trip. I have just found that the heater can waste 1kWh/day just to maintain the temperature, which can seriously affect the main project.
The inention is to use a surplus Uno and mobile phone, and get a new USB host shield and a mains relay - all generally in th manner of Oleg Mazurov in Circuits@Home.
I have an old 5.3v phone charger for auxiliary power, or simply tap in to the charger that I would have to have for the phone.
I'm looking at two different relays, both for DIN rail installation :
I understand this requires a momentary pulse to make and another to break. It does not specify the coil current to do this.
I understand this requires a continuous 5v 100mA to operate and a make-and-hold 5v 0.35mA from Arduino.
This is an all-new arena for me, and I would be glad of any comments, particularly on the relays.