This circuit was found in an English publication from the 70s, an article that teaches how to calculate instruments. The circuit is still current and can be built with an analog indicator of 100 uA.
We found this circuit in an old Mullard (Philips) documentation on the 555 and 556 integrated circuit...
This system makes use of incandescent lamps only and uses a SCR with a full wave bridge for powers...
This two-output circuit was found in General Electric documentation from the 1990s. The circuit uses...