Another way is to use multi-system locomotives that can operate under several different voltages and current types.
The two logical states of a wire are usually represented by two different voltages, but current is used in some logic families.
The different connections give different voltage regulation characteristics on load.
The heaters of the tubes were connected in series, all consequently drawing the same current, but with different voltages across them.
Nevertheless, nothing prevents these units from being allocated to other lines, except of course that they run on different voltage...
In this way, one single voltmeter can be used for a lot of different voltages, large and small.
The differing amounts of radiation falling on each pixel produces a different voltage.
When each cylinder has a different voltage, the gap between the cylinders works as a lens.
But this requires three different voltages and a lot of time and power.
There are numerous types of drivers, with different voltage and current ratings and construction technology.