Show Up W h den e 0 ci n erv e f Science Son Ico Noiseless Burglars Are re Detected by Loudspeaker Alarm r I Device Hears Intruder Before He Makes lakes Sound I IV V WASHINGTON A A A simplified simplified simplified simpli simpli- fied burglar alarm that hears the burglar before he makes a sound and goes off even before i he can get to his safe safe-crac safe cracking ing tools forms the subject matter of a patent recently gr granted here to a New Jersey Inventor So sensitive Is this alarm that should the burglar change the position post tion of ot the tiniest object within the vault nult room a warning gong gon rings and the police pollee dash to the scene A conventional con loudspeaker operated op by a special electric circuit serves ser as t the ear of this Ingenious alarm P- P How Alarm Works Th vibrating diaphragm of ot the loudspeaker sets up sustained si silent silent si si- lent air vibrations within the interior In in- Interior of ot the vault Connecting the loudspeaker to an stem Is Isa Isa isa electrically operated system operated gong s system gong a balanced electrical bridge When setting the alarm system to safeguard the vault this bridge Is adjusted or balanced so that no current current current cur cur- rent can flow from the lou loudspeaker speaker circuit over o the bridge to the gong gong- operating circuit In this condition the loudspeaker diaphragm produces constant vibrations vibrations within the vault or room interior In in- Interior and th the gongs are silent Device la le Sensitive But let some one open the vault molt room door step Into toto the Interior make a tiny hole bole In one of or the walls or as much as change c the position of ot an object In the room and the nature of the air vibrations Is Immediately disturbed Such disturbance dis breaks down the balanced set up of the bridge and starts the the alarm circuit where It t Is detected amplified and sped to a n relay which works worl s the gongs bongs I The Inventor claims t that dint 1 t his pro protective protective pro pro- alarm Is much much- simpler than the present day systems s' s used In I banks s which h for complete protection prot protection c- c tion require specially designed des locks and switches In the d doors ors to control control con con- some alarm device as well as a's alarm system networks embedded In the vault walls and and sound pickup pick up devices In the s safes i s to detect boring and tapping noises |