<P> Other current probes use Hall effect sensors to measure the magnetic field around a wire produced by an electric current through the wire without the need to interrupt the circuit to fit the probe . They are available for both voltmeters and oscilloscopes . Most current probes are self - contained, drawing power from a battery or the instrument, but a few require the use of an external amplifier unit . (See also: Clamp meter) </P> <P> More advanced current probes combine a Hall effect sensor with a current transformer . The Hall effect sensor measures the DC and low frequency components of the signal and the current transformer measures the high frequency components . These signals are combined in the amplifier circuit to yield a wide band signal extending from DC to over 50 MHz . (Wedlock & Roberge 1969, p. 154) The Tektronix A6302 current probe and AM503 amplifier combination is an example of such a system . (Tektronix 1983, p. 375) (Tektronix 1998, p. 571) </P> <P> Near - field probes allow the measurement of an electromagnetic field . They are commonly used to measure electrical noise and other undesirable electromagnetic radiation from the DUT, although they can also be used to spy on the workings of the DUT without introducing much loading into the circuitry . </P> <P> They are commonly connected to spectrum analyzers . </P>

Explain the procedure to test the probe with help of cro