Based on the Linear Technology LTC2054, this -48 V circuit was found in a 2005 manual. The circuit is powered with 5 V and can be used as a shield.
This interesting sensor for RF signals was found in an article in the June 1989 Radio Electronics...
This circuit is from an old documentation but still current for assembly. Just use BC548 instead...
Found in an American publication, this circuit applies to almost any operational amplifier. The power...