For a USB-based power supply, there are cheap modules to monitor current and energy provided. And, on the other hand, there are many devices for measuring AC grid power consumption. However, for DC voltages beyond 12 V and especially beyond 24 V, there are fewer solutions. When you think about small solar systems and electric bicycles, this voltage range is getting more interesting, and that is where this project comes in. To keep things versatile, we have chosen a modular approach. In this first part of this AmpVolt series, we introduce a small board for measuring currents and voltages up to 50 V and 5 A, which can be connected to the microcontroller of your choice.