Q Amateur - 

 Electrician 



^p^d Wireless Operator 



The Construction of a Fifty- Volt 

 Storage- Battery 



THE increasing use of the audion bulb 

 for wireless work brings up a power 

 problem that is by no means easy of solu- 

 tion. The necessity for using 40 or more 

 volts for the amplifying circuit has troubled 

 many of the experimenters who would like 

 to use this efficient form of detector. The 

 small flashlight batteries are in common 

 use more particularly for the portable sets, 

 but while they serve their purpose very 

 well, their first cost and subsequent replace- 

 ment make them out of the question in 

 many instances. The cost of these dry 

 cells is about 30 cents and it is necessary 

 to use 8 or more. Although the audion 

 draws but a small fraction of an ampere, 

 the cells must be discarded before any 

 reasonable returns are made on the invest- 

 ment, as the dry cells deteriorate regardless 

 of whether they are used or not. The fact 

 that the audion requires such a small 

 amount of current suggested that it is 

 possible to construct a storage-battery that 

 will require no replacements and that can 

 be quickly charged at a small cost. 



Two general forms of a storage-battery 

 are given, one for charging from the electric 

 mains having a current in excess of 60 volts 

 and the other for charging from a Bunsen, 

 sal ammoniac or bichromate cell. Each 

 battery consists of 24 cells made of test 

 tubes having an outside diameter of i in. 

 and a wall 3/64 in. thick, the length being 

 about 6 in. The fillers for the test tubes 

 are made of lead tubing ^ in. outside 

 diameter with a wall 3/32 in. thick. The 

 lead tubing is standard stock in assayers or 

 chemical supplies and the test tubes are 

 standard stock. After procuring the 24 

 test tubes, proceed to make a frame A, 

 Fig. I. This style of battery is for use on 

 the ordinary direct current electric main. 

 Lay out and mark the places for the holes 



and bore them with an expansive bit to 

 make a sliding fit for the test tubes. The 

 flared end of the tubes will keep them from 

 slipping through. It will require some 

 care in boring the holes to prevent the 

 board from splitting, and it may be neces- 

 sary to first bore a small hole, say with a 

 3/16-in. bit, for the lead screw of the ex- 

 pansive bit. If the cells are to be charged 

 from primary batteries the construction, of 

 course, is as shown in Fig. 2. 



To make the elements for the battery as 

 shown in Fig. i, cut 23 pieces of the lead 

 tubing, each 12 in. long, as shown in Fig. 3, 



^ +r-k" 



Test tubes 

 used for cells 

 in making a 

 storage 

 battery 



and two pieces, each 6-5/8 in. long, as shown 

 in Fig, 4. The 23 pieces are perforated 

 with a ^in. drill, numerous holes being 

 made for a distance of 5 in. from each end. 

 Then the pieces are bent into a U-shaf>e as 

 shown. The two short pieces are drilled 

 for 5 in. of their length in the same manner 

 and the undrilled end is bent over in the 

 shap>e of an L. Use a sharp drill running 



947 



