Valve Detector and Amplifier – Double Purpose Unit
This early leaflet from 1924 gives specifications and a description of the Edison Bell DPU, PO Reg No. 4547, that could function as a valve detector or a dual amplifier. The leaflet includes a connection diagram of the DPU with an Edison Bell note magnifier and an Edison Bell crystal set as well as an illustration of all three units in one cabinet. Click the thumbnails to enlarge.