Evolution of circuit design for a.m. broadcast receivers: 1900ߝ1935

This paper reviews the major circuit elements of the a.m. broadcast receiver that evolved over the 35-year period from 1900ߝ1935. These include the various valve and crystal detectors that were used: r.f. amplifiers, neutralization, reaction, oscillators, superheterodyne frequency converters, tuning and selectivity, various methods of volume control, including a.g.c, and push-pull amplifiers. The development of the thermionic valve is also covered, as this is closely linked to the circuits that use them. The section on demodulation shows the comparative performance of some of the detector circuits. 106 references.