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.
We found this measurement circuit with a logarithmic scale in an Electronics Now from November 1995....
This circuit assumes that a pulse produced by S1 has a constant duration determined by R1 and C1....
This circuit is used for remote current monitoring. In the original version of the 80s a lamp is...