The Hall Network for Heterodyne Elimination

The Hall Network for Heterodyne Elimination

The Hall Network notch filter circuit is a passive RC circuit that is used to filter out a specific frequency range. It is a third-order circuit, which means that it has three poles and zeros. The notch frequency is determined by the values of the resistors and capacitors in the circuit. The Hall Network notch filter circuit is unique in that it can be tuned over a wide frequency range using a single potentiometer.

The Hall Network notch filter circuit is often used in audio applications to remove unwanted noise or interference. It can also be used in telecommunications and radio frequency (RF) applications to filter out specific frequencies.

The Hall Network notch filter circuit is relatively easy to build and implement. It is also a very versatile circuit, and it can be used in a wide variety of applications.

The Hall network finds its principal use as a band-rejection filter (notch filter), its response curve being similar to that of the twin-T network. It may also be used, similar to the Wien bridge and parallel T, as an audio-frequency meter. The circuit above shows a continuously tunable Hall network which covers the range from 20 to 20,000 Hz in three steps: 20-200 Hz, 200-2000 Hz, and 2-20 kHz. The 5000-ohm wirewound rheostat, R3, is the tuning control. The ranges are changed by the three-pole, three-position switch, S1-S2-S3, which selects the capacitors in threes: C1-C2-C3, C4-C5-C6, and C7-C8-C9.