Magnetic Field Meter Magnetometer Circuit


Posted on Feb 7, 2014

Some experts` think that SMFs may affect the physical well-being of people. If you believe that these experts are right, the magnetic-field meter described will help you find sources of SMFs and determine their strength. These findings may help you reduce the field strength. The input amplifier, based on IC1a, ensures that the signal from the induction coil, L1, is amplified x 101.


Magnetic Field Meter Magnetometer Circuit
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The coil is terminated into a high impedance, so that its output is buffered by the op amp. The integrator consists of IC1B, another of the four op amps contained in IC1. The (active) rectifier, based on IC1c, is, in fact, a differential amplifier that lessens the average voltage by the output potential of the integrator. Since the op amp is powered asymmetrically, the output is a half-wave rectified alternating voltage. This voltage is averaged by R16-C6 or, in case a DVM is used as the meter, by R18-R20- C7. The form factor (2. 22) is corrected by the rectifier. The level matching is purposely carried out by the rectifier since this op amp has a much larger swing than IC1a or IC1b. The principle of the present meter is shown in the block diagram in Figure 1. The induction coil used to detect the magnetic field is represented by an alternating- voltage source, V1, whose average output is 1 µV. The output of the source is amplified x 101 by op amp X1. The op amp is linked to integrator X2 which provides frequency-dependent amplification. For direct-voltage signals this is 1000, for high-frequency signals it is 0. The cross-over frequency is chosen so that the amplification is uniform over the range in which magnetic induction is to be measured (40 Hz 10 kHz). Feedback network R4-R6 automatically ensures that the circuit has a stable d. c. operating point at all times. This makes it possible for relatively inexpensive op...




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