Many of today’s advanced components require an accurate resistance measurement well below the normal range of general purpose instruments. Simpson’s high precision Model 444 Micro-Ohmmeter fits this specialized requirement by measuring resistance from 1 micro-ohm to 20 ohms. It makes the measurement by using an extremely small test voltage (100 microvolt maximum) and a four wire measurement technique. The resistance reading is indicated on a 4- 1/2 digit LCD display using one of two measur-ing modes: An automatic AC measurement mode and a manual DC measurement mode, by limiting the test voltage of the Model 444 to only 100 micro volts, the instrument will not "punch through" contamination or corrosion. An audible tone can be used to indicate resistance values below any selected reading. The Model 444 is powered by a 120 AC source or, from self-contained rechargeable Ni-Cad batteries for field use.