Adjusting Electric Horns

Poverty Bay Herald, Volume LIX, Issue 17947, 26 November 1932, Page 9

Adjusting Electric Horns

YVUIEiSr adjusting an electric horn ol: the motor-driven type, remember that it is better to have it set too loose than too t ight, for in t lie lat ter case it may suddenly refuse to operate. Usually only- very 'little tightening ot the screw is needed, and ii operation is erratic, it is likely- either that the motor bearings require oiling, or that oil. has got to the commutator. AV hen lubricating the bearings not more than one drop of thin oil should be given at the commutator end to prevent this occurring.

'Two adjustments are usually- provided on the high-frequency buzzer horns,'now replacing the motor-driven type. One changes the distance between the magnet core and the diaphragm, and varies the range of movement of the diaphragm, and therefore the power of the horn. . It is correctly- sot at the factory, and should not be changed. The other is at the makc-and-break points, and controls the frequency or pitch of the note, and to some extent the power as well. This will need occasional attention owing to gradual burning of the points. If the points are screwed too hard together the horn will not blow, and the correct adjustment is substantially before this occurs, or failure may occur if the battery becomes partly discharged, or the lights are on. Rapid burning away of the points occasionally causes trouble, and may be cured by- connecting a one micro-farad wireless condenser across them.