Page:Popular Science Monthly Volume 89.djvu/648

 634

��Popular Science Monthly

��A Combination Front and Back Door Alarm-Bell

FASTEN a common alarm clock on a block of wood, after removing the bell and legs. The block must be cut out to expose the back of the clock so

���Diagram of the wires for alarm in connection with the front and back door bells

��it can be wound. Two strips, about 4 in. wide, hold the block from the wall for this purpose. Three light angle strips hold the clock to the board. In the upper corner of the board place the con- tact hook, loosely pivoled and sui>ported by a small brad driven into the board.

When the alarm is released the ham- mer makes contact with the hook, closing the bell circuit. This bell will ring until the hook is thrown back. The con- nection t(j the door-bells are ordinary. Partially run-down batteries from an autoniol)ile may be used for this ar- rangement, connecting a sufficient num- ber in series to ring through the bell circuit.

��Insulating and Decorative Enamel for Electro-Magnets

IN half an ounce of wootl ali-ohol dis- solve one small stick of colored seal- ing wax; shake thoroughly at regular intervals to facilitate comjilete dissolu- tion; put mixture in a tightly corked test tube ur small vial. This mixture will keep indehnitely, and may be ap- plied with a small (-amcl's hair brush. Shake tube well before using. 'I'his is ,1 (|iii( k drying and lustrous cniiiu'l.

��Electric Burner for Making Storage- Battery Connections

IT is well to have all connections on storage batteries fastened to the binding posts in a permanent way by soldering or lead burning. To do this work properly requires an oxygen burner, but the layman is not always sufficiently familiar with the use of this gas to make the proi)er ajijilication, and the appa- ratus is a rather expensive one to keep on hand.

The current taken from the cell is suffi- cient for the heat element and it is only necessary to make connections as shown in the illustration. Almost any par- tially experienced person can fasten the connecter by lead burning.

To produce the proper amount of heat, an old carbon taken from an arc lamp is filed down to a small point to reduce the cross section area and is used the same as a soldering iron. The carbon is fastened to one terminal binding post of the battery with a large wire, using a jMcce of sheet brass around the carbon to make a better connection. Clean the binding post thoroughly to make a good weld. The carbon held on the binding jjost as shown (juickly heats it to a point that will melt the lead; then the carbon is used in the same way

���The current token from the cell is sufficient to weld the connections to the binding-jxists

• IS .III ordinary soldi-ring iron in making a good union ot I he |)arts.

�� �