When working around mains voltages, it can be useful to know whether a given circuit is live or not. While this can be done by direct connection with a multimeter, non-contact methods are available ...

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.

This is a take-off on Mr. Marian’s “Simple Micro Ampere Meter Circuit” that utilizes active circuitry and an analog meter to make sensitive DC current measurements. A reader subsequently asked if it ...