Found in a publication for radio amateurs from the 1980s, this circuit amplifies signals in the 60 kHz band (VLF), Winding data from the ferrite antenna are provided along with the diagram.
This circuit makes use of a special LM195 power transistor not very easy to obtain. The circuit is from...
Found in documentation from the 90s, this circuit can employ other comparators in the series such as...
Suggested by Philips in a 1970 publication, this circuit uses components from that time. No...