Here is a simple circuit for a one transistor Audion type radio powered by a 1.5 V battery. It employs a set of standard low-impedance headphones with the headphone socket wired so that the two sides ...

This circuit is essentially an amplified crystal set. The inductor could be a standard AM radio ferrite rod antenna while the tuning capacitor is a variable plastic dielectric gang, intended for small ...

Back in 1966, a suitable toy for a geeky kid was a radio kit. You could find simple crystal radio sets or some more advanced ones. But some lucky kids got the Philips Electronic Engineer EE8 Kit on ...