This crystal or galena radio is one of the many versions available on this website. This is from a documentation from the 70s. The coil is formed by 50 + 50 turns of wire 28 in a ferrite rod.
Synchronized key. This circuit was found in a 1966 General Electric documentation. Modern...
This oscillator by Wien bridge is based on stabilization by a small incandescent lamp. The...
This oscillator with the PLL 4046B was obtained from a 90s Radio Electronics. The circuit...