Voltio from Befaco is an accurate manual voltage source and precise transposing aid for oscillators and filters. The module is primarily designed for the exact calibration of Eurorack modules such as oscillators and filters, but also serves well as a laboratory device or for calibration in DIY projects and in an electronics workshop. Voltio generates exact voltages that correspond to the notes of the equal-tempered 12-tone scale over a range of ten octaves. The voltage range can be switched between 0-10 V or +/- 5 V. In practice, Voltio is used as a reference for calibrating analogue devices and as a CV offset to set a second oscillator to a desired note. Commercially available multimeter probes can be connected to the banana sockets for hands-free work in the electronics lab.