In the course of answering literally thousands of application calls, we encounter many customers who specify 4½ digit meters for applications in which a lower-cost 3½ digit meter would be adequate. For example, monitoring the output of a 30Vdc supply with a 200V full-scale input range 4½ digit meter will result in a display reading of "30.00" with a resolution of 0.01V (1/100 of a volt). A 200V full-scale input range 3½ digit meter will display the same 30V input as "30.1" (1/10 of Volt resolution).
Most voltage and/or current monitoring applications do not benefit greatly from the extra resolution 4½ digit meters offer, in fact, in many applications, the extra digit may result in unwanted, difficult-to-view, display bouncing of the last digit. In general, use a 4½ digit meter only when values over 1999 must be displayed in their entirety for clarity or calibration purposes. If you are not sure which meter to use in your application, don't hesitate to contact DATEL-we are more than happy to discuss your requirements in greater detail! (800)233-2765(USA).
Do I need a 3½ or a 4½ digit meter?