Page:Popular Science Monthly Volume 88.djvu/489

 Making a Master Vibrator for Automobiles

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��THE ignition of any motor car equipped with a vibrating coil may be greatly improved by the insertion of a device known as a "master vibrator" in the circuit. It is very difficult to ad- just the separate vibrators for each cylinder, so that sparks of the same in- tensity are produced in each of the cylinders ; but by substituting one vi- brator for the sev- eral originally used, this difficulty is overcome.

A discarded unit coil may be secured from any garage or second - hand parts

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��The master vibrator as completed

��house, the only requirement being that the vibrator on the end of the coil shall "buzz" when current is passed through the terminals. It is not necessary for this coil to deliver a spark. Hence the condition of the secondary winding is unimportant. A single coil which has been removed from a set of two or more, will prove very satisfactory, the box not being required.

This coil will have three terminals, two for the battery current and one that led to the spark plug. Connect four or five dry cells, as shown, and touch the two wires to any two of the three ter- minals until a pair is found which causes the vibrator to operate. Comiect either one of the two terminals just found to the third (the one that did not cause vibration). This short-circuits the secondary winding of the coil, and makes it inoperative. The two terminals which did cause vibration are to be used. If this coil has no protecting box, it will be best to make one of a size that just takes the coil, with a cover hinged or screwed on over the vibrator end. The two terminals to be used should be brought to the outside of this box, pre- ferably through the .end opposite the cover, and the box containing the coil should then be mounted solidly on the dashboard by the side of the two, four or six-unit coil-box already there.

It will now be necessary to prepare

��the coils on the car which have been in use for ignition purposes. A per- manent electrical connection must be made between the two platinum points on each vibrator. This may be done in either of two ways. The best meth- od is to run a short piece of copper wire from the metal piece carrying the vibrator-spring to the metal piece on which the other platinum contact is carried. This allows the current that formerly flowed from one contact to the other, to pass through the cop- per wire, and the spring will no longer tremble when current flows. A quicker, although not as satisfactory a method- is to turn the adjusting screw^ on each coil until the two contacts are held tightly together, making the circuit complete at all times and preventing vibration of the spring.

The wires running from the coil originally used to the timer on the en- gine and to the spark plugs, are to re- main, but all other wires to battery, magneto and switches are to be re- moved from the coil terminals. This completes the preparation of the coil formerly used.

If the car is equipped with two sets of batteries, or a set of batteries and a magneto (such as the Ford magneto),

����When the contacts are properly adjusted,

the addition of this master vibrator greatly

improves the ignition circuit

it will be necessary to fit a switch hav- ing three terminals, one for the batter- ies, one for the magneto or reserve set of batteries and the other for the coil connection. This switch will have

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