EMI107 - Differential DC/AC Voltmeters скачать в хорошем качестве

EMI107 - Differential DC/AC Voltmeters

Differential DC/AC Voltmeters Definition: The voltmeter which measures the difference between the known and the unknown voltage source is known as the differential voltmeter. It works on the principle of comparison between the reference and the unknown voltage sources. A basic circuit of a differential voltmeter based on the potentiometric method is sometimes also called a potentiometric voltmeter. In this method, the potentiometer is varied until the voltage across it equals the unknown voltage, which is indicated by the null indicator reading zero. Under null conditions, the meter draws current from neither the reference source nor the unknown voltage source, and hence the differential voltmeter presents an infinite impedance to the unknown source. In order to measure ac voltages, the ac voltage must be converted into dc by incorporating a precision rectifier circuit.