File:EB1911 Telegraph - Vacuum Thermal Detector for Electric Oscillations.jpg

English: A form of thermoelectric receiver has been devised by J. A. Fleming (Phil. Mag., December 1906) as follows:—It consists of two glass vessels like test tubes one inside the other, the space between the two being exhausted. Down the inner test tube pass four copper strips having platinum wires at their ends sealed through the glass. In the inner space between the test tubes one pair of these platinum wires are connected by a fine constantan wire about .02 mm. in diameter. The other pair of platinum wires are connected by a tellurium-bismuth thermo-couple, the junction of which just makes contact with the centre of the fine wire. The outer terminals of this junction are connected to a galvanometer, and when electric oscillations are sent through the fine wire they cause a deflexion of this galvanometer (see figure: Tellurium-bismuth Vacuum Thermal Detector for Electric Oscillations. a b, constantan wire; c d, thermojunction; G G, galvanometer terminals; O O, antenna and earth terminals.).