Megger: Another common method of measuring resistances above 50 M Ω is the Megger (megaohmmeter) shown in Fig. 10.23(a). This instrument is used to measure very high resistances, such as those found in cable insulations, between motor windings, in transformer windings, etc. Normal (shop) VOMs do not provide accurate indications above 10 MΩ be­cause of […]

Transistor Tester

Transistor Tester: The term Transistor Tester (or analyser) used in this text is for instruments giving quantative measurements of transistor parameters. The tester should be able to provide direct readings for atleast two important measurements, such as: A value for the forward gain in the common emitter configuration (hFE for ac gain or hFE for dc […]

Vector Impedance Meter

Vector Impedance Meter(Direct Reading): If some knowledge of the reactive and resistive factors is needed, in addition to obtaining a direct reading of the magnitude of the impedance (Z), a test method for determining the Vector Impedance Meter may be employed. This method determines Z in polar form, that is, it gives the magnitude IZI and […]

Phase Sensitive Detector Circuit

Phase Sensitive Detector Circuit: Figure 10.4 shows a Phase Sensitive Detector Circuit (or phase meter) for comparing an ac, signal with a reference signal. The Phase Sensitive Detector Circuit produces a rectified output, which is fed to a dc meter, to illustrate clearly that the output of the phase sensitive detector swings the zero centre […]

Stroboscope Definition

Stroboscope Definition: Stroboscope Definition – The stroboscopic principle uses a high intensity light which flashes at precise intervals. This light may be directed upon a rotating or vibrating object. The stroboscopic effect is apparent when the rotational or vibratory speed is in a proper ratio with the frequency of the light flashes. Most stroboscopes consist […]

Output Power Meters

Output Power Meters: The Output Power Meters is designed to directly measure the output power in an arbitrary load. The instrument provides a set of resistive loads to be selected for power measurements. In addition to power, the output meter can be used to measure impedance and frequency response characteristics. A simple circuit is illustrated […]