Perfect functions in one set of voltage and current meter measuring current power from the measuring circuit no separate power supply isolated power supply On-Board wire information: Thin red wire VCC: Power supply input positive (3.5~30V) Thin black wire GND: Power supply input negative (3.5~30V) Thin yellow wire VIN: Measured signal input positive (0~100V) Thick red wire I+: Current input positive (Negative in the power supply must be connected in series) Thick black wire I-: Current input negative (Negative in the power supply must be connected in series?)