A novel high common mode DC ammeter

A wide-range DC ammeter for laboratory research, capable of operating at high voltage, is described. Low cost, easy construction, versatility, and commonly available components were desired design requirements. The ammeter consists of a series-connected microammeter and milliammeter. Specifications include linear current sensing from 1 mu A to 1 mA with a fixed linear scale resolution of 1 mu A/div for the microammeter and 20 mu A/div for the milliammeter with an accuracy of +or-2.5% of full scale for both meters, operating voltage up to 30 kV DC, short circuit, and RF transient protection. The principles of operation and a method for calibrating the ammeter are included.<
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