1910 radio, crystal set

[old_coot88]

There was an interesting project in Popular Electronics (it might have been Electronics Illustrated) when hobby transistors first became available back in the late '50s. It was for a "free power" amplifying crystal set. It consisted of two receivers running off a single longwire antenna (though the 'crystals' used were 1N34 diodes). The first receiver used the carrier of a strong local station to provide rectified DC (a volt or so) to power a one-transistor amplifier. The second receiver could tune to any station and feed the audio to the transistor which amplified it, using nothing but the "free power" from the first station's carrier.