Found in Popular Electronics, this sophisticated short-wave receiver requires a lot of skill from an eventual assembler. The coils are commercial types of the time, used in commercial radios.
This circuit can be used in demonstrations or science fairs. The circuit uses headphones and can...
We found this wiretapping circuit in a publication from the 90s. The circuit allows the cable...
This circuit uses a resonant reed switch at the trigger frequency. The circuit is from General...