THAT HUMMING SOUND IN CRYSTAL-SET PHONES

Radio Record, Volume I, Issue 3, 5 August 1927, Unnumbered Page

THAT HUMMING SOUND IN CRYSTAL-SET PHONES

HOW It MAY BIf CURED. Some crystal listeners whose homes are connected tu an electric supply may find that there is a slight continual hum in their headphones. ‘This interference is caused by nearness to the electric wiring in the house or by the influence of street mains upon the aerial, which may be running more or less parallel to the street wires. Here is a simple method that may eradicate the trouble. Place a_ slightly-moistened finger on the earth terminal of the set, and if this cuts out the hum, then a permanent equivalent to the finger can be tried. ‘This consists of a length of a few feet of bare copper wire attached to the earth terminal of the set and allowed to run loose along the floor. It mav improye matters to connect the free end to a metal object, perhaps a foot-square sheet of metal placed under the floor covering, but neither this nor the wire is to be directly connected to earth.