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 ...

This is the simple version of a white LED lamp that can be directly powered from mains. It can give ample light even for reading purpose. Capacitor Cx along with diodes D1 through D4 forms the AC step ...

Editor's Note: Here's another take on the transformerless AC line power supply, which finds use in some well-insulated, low-power devices. Our technical reviewer pointed out that C ac should be an ...

This file type includes high-resolution graphics and schematics when applicable. Low-power applications such as e-meters (electricity or energy meters) often require a simple ac line-powered supply ...