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 ...

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 ...

Alternating current (ac) or direct current (dc) circuits are capable of carrying very different currents, as illustrated by the ratings on the switch in Figure 1. This is why it’s so important for ...