Hall-Effect Rectification

Hall-effect rectification is the proposal that the synchronous reversal of Hall polarity with an alternating magnetic field or alternating current can be used to convert AC into pulsating DC. It is the operating principle claimed for Palmer H. Craig's device and patented in US1822129 — System & Apparatus Employing the Hall Effect and GB274112.

The proposed mechanism

In Craig's arrangement, alternating current is passed longitudinally through parallel conducting plates separated by insulating sheets, while a solenoid produces a perpendicular magnetic field. Because both the longitudinal current and the field alternate, the transverse potential difference is direct. The transverse potentials of the individual plates are connected in series at their edges, so that the small per-plate Hall voltages sum.

The patent describes the arrangement as a "perfect rectifier" producing no distortion, usable as rectifier, amplifier, oscillator, and detector, and combinable with electron tubes. The patent reports that with four amperes of 60-cycle alternating current passed through a 12-turn coil and then through the conductive films connected in parallel longitudinally, the resulting pulsating direct current component across each conductive film is approximately 50 microvolts; when the films are connected in series transversely, 200 microvolts may be obtained. It also states that the resultant transverse pulsating direct current is "several volts for only one milliampere flowing through the field coil and longitudinally through the conductive films in parallel."

The counter-explanation

Harry F. Breckel's 1927 tests found the apparent rectification to be a Thermal Junction Rectification Artifact — a unidirectional transverse current of the order of a few millivolts produced by lead and copper contacts on the bismuth films when heated by the current, with very low output-to-input efficiency. Meter readings were largely due to inductive effects on wires and meters in the magnetic field, and radio reception results were zero.

See also

Hall Effect, Additive Principle (Series Hall Potentials), comparisons/comparison-craig-hall-effect-claims-vs-evidence.