When we think of a spark gap radio transmitter, most of us immediately imagine an early twentieth century ship’s radio room or similar. Most of us know these transmitters as the first radio systems, ...

Speakers appeared in the late 1800s. Most early versions were horn shaped and didn't require electricity or an electrical impulse to operate. With the invention of the wireless telegraph and radio in ...

The squat, bland, concrete-block building on a side street in St. Louis Park looks like it could be a meat locker, an auto parts warehouse or a CIA safe house hidden in plain sight. But step inside, ...