This can be built easily by connecting 9v battery, a potentiometer, and a multimeter on current mode in series. The potentiometer basically controls the current

This can be built easily by connecting 9v battery, a potentiometer, and a multimeter on current mode in series. The potentiometer basically controls the current and the multimeter displays how much you are putting in yourself. I'm curious on what the benefits of this is but also scared of the side effects if there are any. Anyone else tried this?