This simple receiver of two transistors for the 80-meter range was found in an American documentation from the 1980s. The transistors admit equivalents and the antenna must be long.
This interesting control circuit was found in an Electronics Now from 1988. Through it we can...
This circuit causes neon lamps to flash randomly from a low voltage supply (1.5 to 3 V). The...
Any operational amplifier, like the 741, can be used on this oscillator whose frequency depends on R1...