Valhalla Scientific Models 2100 and 2101 Digital Wattmeters are accurate, low-cost In­ struments to aid engineering, production test and quality assurance departments in the determina­ tion of product power consumption from DC and AC power lines. The instruments feature dual, in­ dependent digital displays. One display provides a continuous indication of True Power in Watts. The other display is sw itch selectable between Amperes (True RMS) and Volts (True RMS). 1-3 The Model 2100 and Model 2101 provide a fast and convenient method of determining product ef­ ficiency, power factor and true RMS current. Phase angle relationships may be calculated through utilization of the displayed digital data. 1-4 The Digital Wattmeters use a unique four- quadrant complex waveform analog m ultiplier to derive a DC signal equivalent to the integrated pro­ duct of the instantaneous value of line voltage and current. The resultant wattage value is converted for presentation on a 4-1/2 digit display. Power ranging provides maximum resolution from 10 m illiwatts to 12000 watts on the Model 2100 and from 1 m illiw att to 6000 watts on the Model 2101 True RMS current from 100 microamperes (max resolution) through 19.99 amperes with a Crest Audio fac­ tor of 2.5:1 may be monitored by selecting the cur­ rent display with the front panel switch. True RMS voltage from 7.5 volts to 600 volts may be monitored on the Model 2100 by selecting the voltage display. On the 2101 the range is from 1.5 volts to 300 volts. Four binding posts on the rear panel provide convenient means of making the measured line and load connections. 1-5 The Digital Wattmeters are designed to operate from selectable 115/230V AC power. The loads may be operated from power sources up to 600 volts on the Model 2100 and up to 300 volts on the Model 2101 These sources may be indepen­ dent of instrument power and may be DC, or AC from 40 Hz to 20 KHz. Peak voltage limitation is 1500 volts for the Model 2100 and 750 volts for the Model 2101 There are three selectable current display ranges identified on the front panel as .2,2 and 20 amperes. DC current may be displayed up to 0.5000, 5.000 and 20.00 amperes. AC sinewave current may be displayed up to 0.3500, 3.500 and 20.00 amperes. Voltage display ranges are also selectable in three steps; 150.00, 300.0 and 600.0 on the Model 2100 and 30.00, 150.00 and 600.0 on the Model 2101