Figure 1-17. ESI, Model 230B MOD, Resistance Bridge.
ESI, Model 230B MOD, Resistance Bridge (fig. 1-17) is an extremely accurate, high resolution, guarded Wheatstone
bridge. The bridge will measure a continuous range of resistance values between 0 and 12 gigaohms (12,000 megohms)
with a resolution of 10 microhms per dial division on the lowest range. A five-place direct readout combined with eleven
ranges enables the operator to make leakage resistance measurements in thousands of megohms or contact resistance
measurements in millohrns with equal ease. The internal switching and interconnection circuit is arranged to eliminate
sources of error found in many conventional Wheatstone bridge circuits. A dc power source and a dc detector for
observing a null balance are necessary to operate the bridge.
Figure 1-18. Hewlett-Packard, Model 410C, Voltmeter.
Hewlett-Packard, Model 410C, Voltmeter (fig. 1-18) can be used to measure dc voltage and dc current; ac voltage and
resistance. Positive and negative dc voltages from 15 mV to 1500 V _ Y full scale and positive and negative dc currents
from 1.5 microamperes to 150 milliamperes full-scale can be measured. Resistance from 0.2 to 500 megohms midscale
can be measured.