If your goal is to save on electricity, you must first measure the ac current flowing through your appliances. The formula for power is the product of the ac line voltage and the measured current.

[Big Clive] had some 22mm digital AC voltmeters, made to put in a panel. There was a time when this would have been a significant pain, since it required you to make a large square hole. Of course, in ...

Testing for failure with a multimeter is only partially effective, whereas a dedicated optocoupler testing circuit provides ...