Hartley for 1 MHz (CB25588E)

This oscillator was found in the July 1993 Electronics Now magazine. The coil is wound with 28-wire in a 0.5 cm shape.

Transistor Audio Oscillator (CB12375E)
This circuit is from a 1974 publication, but it can still be easily assembled today with BC548...
Air Pressure Change Sensor (CB6528E)
Found on Popular Electronics in the 1980s, this circuit detects a change in air pressure using a...
Audio step for earphone (CB20560E)
This 3-transistor amplifier stage was found in documentation from 1963. The transistors are made...