Columbia D DC meter (1910s)	Up	Next
The Type D meter has several radical differences from other DC meters. First, the armature has only 3 coils instead of the 8 normally used. Secondly, the current (and light-load compensation) coils are mounted at a 45-degree angle, and the light-load adjustment is a tapped resistor to vary the voltage fed to the armature.	Electrical Meterman's Handbook