Found in a 1969s American documentation, this circuit uses transistors from that time. The configuration can be adapted to use modern equivalent components.
Found in an Electronic Design from the 90s, this circuit uses components from that time....
We found this amplifier with 50 MΩ input resistance in the May 1989 Radio Electronics magazine. The...
This setting appears elsewhere in this section. This was obtained from an American 1980s...