The circuit in Figure 1 provides a low-cost, isolated ac-line monitor that measures ac-line-voltage level and has some other unique capabilities. The analysis of the circuit is straightforward: When ...

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 file type includes high-resolution graphics and schematics when applicable. For applications such as motor control or power supplies, it’s often necessary to know whether the ac line is at 120 V ...

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 ...