In 1914 the tube was not yet comon for use as a detector. Various systems were being improved. In 1914 W.H. Marchant writes the following about detectors:

World
of
Wireless

Detectors of electrical oscillations

The detectors used in Radio-Telegraphy may be broadly divided into two classes: those that are potential actuated and those that are current actuated: the former are always joined across the terminals of the condenser, as the potential differences are largest there, and the latter or current-actuated variety are connected in series with the condenser. Detectors may also be further subdivided into classes -namely, imperfect contact devices, such as the Marconi coherer; rectifying devices, such as the Fleming valve and the carborundum detector; electrolytic detectors, as those of Fessenden and Schlomilch; the thermo-electric type, formed of galena against graphite, and various other combinations, and those that depend for their action on the alternation of their magnetic properties: in this class is the Marconi magnetic detector.

• The Coherer
• Lodge Muirhead Coherer
• Electrolytic Detector
• Carborundum Detector
• Fleming Valve
• Thermo Electric Detector
• Magnetic Detectors