Q: I have a newly converted condo (it used to be an apartment), and it has electric wall heaters. They are 220 volts. I also have an electric fireplace with a built-in heater. Cheesy yes, but instant ...

A decade or so ago, I designed a simple circuit that included a quad optoisolator arranged in a full-wave analog-multiplier bridge (Figure 1). It sensed and calculated watts of ac-power consumption ...

If you read our recent feature about the Tal-y-Llyn Railway, the world’s first preserved line, you may have taken a while to watch the short film about the railway in the early 1950s. It was the work ...