This uses a nice case containing a high-quality 100 microamp meter with 0-10 and 0-3 scales. It has separate analog and digital functions. The analog passive voltmeter has 3, 10, and 30V scales at 10 Kohm/volt. The analog ammeter has these scales at a drop of 60 mv: 100 and 300 microamp; 1, 3, 10, 30, 100 and 300 milliamp; 1 amp. The digital function has controls to select a field from a serial input, convert the ascii values to a binary number and display it on the meter with auto-ranging. It has digital displays for the field and the range.

This is the front and rear of the meter:

Here are the circuit diagrams

Here is the code