The Hewlett-Packard Model 740B is a precision multifunction instrument that operates as a dc standard voltage source, a dc differential voltmeter, a high impedance dc voltmeter and a dc power and voltage amplifier. The instrument is designed for use in both the standards laboratory and the field. 1-5. DC STANDARD. 1-6. When used as a dc standard, the Model 740B provides output voltages from 0 to 1000 V in 4 decade ranges: 1 V, 10 V, 100 V and 1000 V. The output voltage on each range can be set with 6-digit resolution. The output voltage is accurate to within ±(0.002% of setting + 0.0004% of range). Output voltage is indicated on digital readout tubes (first five digits) and the meter (sixth digit). Maximum output current is 50 mA on the 1 V range decreasing linearly to 20 mA at full output voltage on the 1000 V range. The front panel CURRENT LIMIT control allows adjustment of the maximum output current from approximately 10% to 100% of the available output current at each voltage setting. Remote sensing allows the output voltage to be regulated at the load, eliminating the effects of lead resistance. The output circuit is floating and guarded. A pushbutton switch allows the output voltage to be switched on and off without resetting the voltage dials. 1-7. DIFFERENTIAL VOLTMETER. 1-8. Used as a differential voltmeter, the Model 740B measures dc voltage on seven decade ranges from 1 mVto 1000 V. Voltage measurements are accurate within ± (0.005% of reading + 0.0004% of range + 1 /xV). The measured voltage is indicated on five digital readout tubes (first five digits) and the meter (sixth digit). High input resistance (>10*0 Q on all ranges above 10 mV) is maintained regardless of whether or not the voltage dials are nulled. The input circuit is floating and guarded, allowing accurate measurements to be made under conditions where ground loops are a problem. 1-9. HIGH IMPEDANCE VOLTMETER. 1-10. The Model 740B can also be used as a ± 2% floating and guarded dc voltmeter with 10 voltage ranges from 1 jiV to 1000 V. Input resistance is > lO1^ £2 on all ranges above 10 mV. The measured voltage is indicated on the meter. 1-11. AMPLIFIER. 1-12. The Model 740B can be used as a dc power amplifier in the Voltmeter and Differential Voltmeter modes of operation by connecting the source to the input terminals and taking the output from the output terminals. Voltage gain is unity on the 1 V range and higher, but increases in 20 dB steps on the lower ranges to a maximum of 60 dB on the 1 mV range. Output current characteristics are the same as the DC Standard mode and the high input resistance characteristics of the Voltmeter and Differential Voltmeter modes are retained. Voltage gain accuracy is ±(0.01% + 5 ppm of range + 2 uV). 1-13. The Model 740B can also be used as a voltage amplifier in the Voltmeter and Differential Voltmeter modes with up to 120 dB of voltage gain available at the rear panel RECORDER OUTPUT terminals. Voltage at these terminals is directly proportional to meter deflection and is 0 to ± 1 V on all ranges, 1 µV to 1000 V.