BVWS Bulletin Volume 5, Number 4 (March 1981)

BVWS BulletinVolume 5, Number 4 (March 1981)

Front cover:  Edison Swan 'One-Der' receiver employing an unusual double triode valve.

Page Title Summary/Notes
50 The Power Valve 1920-1940 Part 1.
Philip Beckley
Early valves designed to drive loudspeakers; Mullard PA1 and PA2, Ediswan PV1 and PV2, and Marconi-Osram LS1, LS2 and LS3
53 The Edison Swan 'One Der'.
Anthony Constable
An unusual receiver using a single ES220 double-triode valve.
56 Loudspeakers Part 5.
David Read
The moving cold loudspeaker.
59 Re-Inventing The Wheel.
Desmond Thackeray
Carborundum and its rectification effect / use as a detector.
62 The Compact Variable Disc Condenser.
Anthony Constable & Roger Snelling
The disc condenser developed by C.S.Franklin and patented in 1907.