MEASUREMENT SYSTEM FOR INPUT BIAS –OFFSET CURRENTS OF AN OPERATIONAL AMPLIFIER
A very simple microprocessor (µP) -based dedicated instrument is designed here.' The Overall system design consists of both hardware and software designs. This set-up yields the exact values of input bias and input off-set currents on the µP display panel, one after the other, when the operational amplifier (OP- AMP) under test is connected across the test terminals.
Microprocessor Based Instrument for Resistance and Diode Testing
The component tester reported in this paper is a microprocessor based instrument. It is used for evaluating resistances in the range of 100–10M Ohms divided equally over five automatically selected ranges. It has also got the capability of testing silicon diodes for their usefulness. The diode can be connected in any particular fashion. The hardware circuit is IC based and includes resistance detector, relay drivers, buffer, constant current source, diode tester, analog to digital converter and Intel 8085 based programmable microprocessor kit.
Microprocessor-based resistance measurement
The paper deals with microprocessor-based resistance measurement of electrical RL circuits by sampling values of the current and voltage. Special attention is paid to the relation between the time required for this measurement and the accuracy attained. This is a problem associated with circuits having a very high electrical time constant, such as windings of large transformers or superconducting coils. The suggested method permits shortening of the required resistance measurement time, which in turn realizes a significant overall time saving. In addition, it permits overcoming essential measurement errors which may occur when the test is performed during a thermal transient. Different measurement errors are analyzed and a statistical method which leads to significant improvement of the result is presented.