DIODE VALVE CHARACTERISTICS APPARATUS WITH DC REGULATED POWER SUPPLY – GUPTA BRAND Posted on February 25, 2017May 2, 2017 by admin Objective: Vl Characteristics of Diode Valve at various filament voltages. Features: Instrument comprises of DC Regulated Power Supply 0-250VDC/30mA, Variable AC Power Supply 6.3 VAC/1Amp,two round meters for voltage & current measurement