The principles behind two different designs of inductive power meter are presented. They both make use of the microphone input of a computer which, together with a custom-written program, can record the instantaneous power of a domestic electrical appliance. The device can be built quickly and can be calibrated with reference to a known power device such as an electric kettle. Typical power-versus-time profiles are shown for a kettle, a dishwasher and a fridge-freezer. The components are cheap and the cost may be recouped many times over from the resultant energy saving. Custom software will be made available free of charge to anyone who requests it. It is hoped that students attending poorly resourced schools will be able to make power loggers for educational use.