THE HANDY MAN’S CORNER.

Otago Witness, Issue 3869, 8 May 1928, Page 10

THE HANDY MAN’S CORNER.

FITTING ELECTRIC BELLS

(Special for the Otago Witness.)

The fitting of an electric bell that can be sounded at will from any one of several different places is not a difficult matter for the handv man. The requirements are: a good quality electric bell, two or three Leclanche batteries or dry batteries, the requisite number of press buttons or switches, and the connecting wires. This is known as bell wiie. and the best quality should be bought; a standard coil is the most economical, since any surplus will come in handy for o.dd jobs. The wile is supplied* in two forms: “single,” that is one wire in an insulating covering, ana “ twin,” which consists of two separate wires each insulated and the whole enclosed in one outer covering. Twin wire is preferable for long, unbroken runs, but the single wire is better for local connections; a coil of both kinds will be the best investment. In addition, obtain one or two packets ot small “ insulated staples,” which are used for fixing the wire. The next step is to decide the position of the various presses and to fix them with screws or. rawl plugs. Then' fix the bell in position, placing this wherever its sound will best be heard by those concerned : a good place is on the underside of a flight of stairs in the hall, or above the door in the kitchen. A cool dry place for the batteries is now required, and this should be as near to the bell as circumstances allow. If the battery be placed in a neatly stained wooden box attached to the wall, it will be out of the way, and the batteries are not likely to be disturbed. The various parts having been placed in the chosen positions, they have to be connected together by the wires, an operation known as wiring and shown in diagrammatic form in Fig. 1. In a new building the wires are generally embedded in the plaster covering of the walls and ceilings, but this is seldom possible when fixing the bells at a. later time, and they will generally have to be run on the surface.

Start with the twin wire at the press farthest away from the bell, bare the ends of the two wires and attach an end to each of the two fixing screws on the press, somewhat as shown in Fig. 3. The wire is inserted from the back, for which purpose the press should be removed. Take care that the two wires do riot touch anywhere near the parts where they are exposed by the removal of the insulation.

From this press, lead the wire, in as neat a manner as possible, up the wall to the frieze rail ■ or down to the wainscote and secure it with a staple or two as shown at C, in Fig.- 2. Experience alone can dictate the best “ run ” for the wire, but when it is possible to get easily to the next press it will be advisable to do so, and to “ loop in ” to it as shown in Fig. 4. This is done

by first removing the outer covering for a length of several inches, then doubling over the two wires as shown and scraping or burning off the insulation at the bend. The exposed wires are then connected to the press as before. The two wires are then taken on to the other press as shown at 1-2-3 in Fig. 1, a single wire is connected from either of the two twin wires to one terminal of the bell A, and the second of the twin wires is connected to the plus side of the battery. The battery (B) will consist of two or three cells, and these have now to be connected together in series. This is done by connecting the minus terminal of the first battery to the plus terminal of the second, and the minus terminal of the second to the plus terminal of the third battery. Thus there remains one free terminal on the battery—and this is then connected by a single insulated wire to the other terminal on the bell. If all the connections have been correctly made, when any one of the presses is pushed the bell should ring. If it does not, look to the adjustment of the presses themselves and see if they all make proper contact, remedying any defects. Also note if all the wires are nicely connected and the insulation completely removed at the contact places. Finally test the battery itself, either with a voltmeter or a flash lamp bulb of suitable voltage, and look to the adjustment of the contact blade and points on the bell. If when a Dress is pushed the trembler on the bell vibrates a" little, a tightening of the adjustment screw will remedy the matter and the bell will soon ring.

Should it not be possible to stop the bell ringing without taking one of the wires off it, that is an indication that a short circuit exists across one of the presses; probably the bared ends of the wires are touching, a matter that is speedily detected'and remedied.