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 setting appears with variations at various points on this site. This is from a Motorola...
This circuit indicates through LEDs when an automotive fuse is open. ...
The circuit shown in the figure generates a rectangular signal whose frequency depends on C1. For...