It is an instrument with a mobile coil having the same structure and dimensions as the one described previously, from which it differs only in the resistors which, being connected in series to the coil, make it usable as a voltmeter.

As indicated underneath the scale, it has an amperometric range of 8.5 amperes. It is accessible by means of a common (+) wire clamp which is connected directly to one end of the coil by means of one for the 3 volt range, which is connected to the other end of the coil by means of a 350 ohm resistor and by another for the 150 volt range which is connected to the coil through a 17,300 ohm resistor in series with that of 350 ohms.

The two resistors consist of two small coils of thin wire; the scale has 150 divisions.