The voltmeter is an expanded scale type that indicates small voltage steps over the 10 to 16 volt range for 12 volt batteries and over the 22 to 32 volt range for 24 volt batteries.
http://www.solorb.com/elect/solarcirc/vom/index.html
It measure the voltage on a 12V nominal lead acid rechargeable battery. Lead acid batteries normally spend their working lifetime in the voltage range of 11-15 Volts. This meter circuit was designed to show the voltage range of 10-15V on an analog meter movement, it can be used to show the battery charge state from empty to full.
http://www.solorb.com/elect/solarcirc/xsvmeter/index.html
in a three-phase system
http://www.edn.com/archives/1995/090195/18di1.htm
a visual indication of whether a sensed voltage is above or below its nominal value, provides different-color indications if the sensed voltage is above or below the preset value
http://www.edn.com/archives/1996/101096/21di_04.htm
has 0-10A full scale
http://www.solorb.com/gfc/elect/solarcirc/imeter/index.html
41/2-digit picoammeter uses an integrating transimpedance amplifier to achieve a resolution of 0.1 pA
http://www.edn.com/archives/1997/071797/15di_04.htm
provides a visible indication of positive and negative current pulses whose amplitudes can vary from 20 to 150 mA
http://www.edn.com/archives/1994/010694/01di6.htm
operated from 12V battery and shows it's voltage
http://www.solorb.com/gfc/elect/solarcirc/vom/index.html