I seem to be doing power monitoring projects a lot, started with this one, then moved on to this, then this and now I am again putting up a power monitor.. This particular will be using a small transformer with two secondary windings: one will be used to power the circuitry and the other for voltage sensing. PCB is 5*5 cm and will have screw terminals for 230V and a current sensor. On-board is a RFM12B module that will transmit the readings to a base station. The processor is an Atmega328 running on its internal RC oscillator. The circuitry will run on 3.3V to simplify things. Here is how it is taking shape, comments are welcome:
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