It is possible, by means of four cells of rectifier, to so connect them that "both halves of the alternating current wave are utilized" and the spaces are filled up as shown in the lower part of Figure 55.
[Illustration: FIG. 56.—Diagram showing how a Four-Cell Rectifier is connected. The Alternating Current Source is connected to C and D. The Direct Current is taken off at A and B. The Electrodes marked A, A, A, A are the Aluminum Electrodes. L, L, L, L may be Lead or Iron.]
The current which would normally be in a reverse direction, and therefore below the straight line, has been completely reversed so that it flows in the same direction as that above the line.
Figure 56 shows how to connect four cells of rectifier in order to secure this result.
An electrolytic rectifier composed of cells approximately 5 x 7 inches, as described, will not efficiently handle a current of over two to two and one-half amperes. A four cell rectifier will operate to the best advantage on a voltage over 50, and for that reason it is always best to use a lamp bank or step-down transformer in connection with it.
When the solution in a rectifier becomes hot it will not operate as efficiently as when cold. The solution becomes exhausted after a certain amount of usage and requires renewal. This condition will be indicated by the failure of the rectifier to operate properly. The old solution should then be thrown away and the jars and electrodes washed and cleaned thoroughly before the new solution is poured in.
[Illustration: FIG. 57—A Complete Four-Cell Rectifier connected together and Mounted in a Tray.]
CHAPTER V. HOW TO BUILD A STEP-DOWN TRANSFORMER FOR REDUCING THE 110 VOLT A. C. FOR EXPERIMENTAL PURPOSES.
A Step-Down Transformer will reduce the 110 volt alternating current to a low voltage. These low voltage currents are still alternating but will operate almost all sorts of direct current apparatus with the exception of permanent magnet type motors which are now practically obsolete.
A suitable step-down transformer may be used to operate electrical toys, such as small fans, motors and miniature electric railway trains, ring bells, light small lamps, operate spark coils, etc., in fact the different uses are practically unlimited, depending only upon the ingenuity of the experimenter.