Charginb Accumulators from Daniell Cells.

Radio Record, Volume I, Issue 20, 2 December 1927, Page 13

Charginb Accumulators from Daniell Cells.

A Grey Lynn reader writes to say that some time ago he was charging accumulators with Daniell cells with different solution to that specified in the "Record." His experience was that the cells required watching, and occasionally it was mecessary to correct a tendency for the copper sulphate to work through the porous pot to the zine. ‘This reader had the ‘outfit in use for over three years, and states that it gave very good results. He also sends a description of a different form of Daniell cell known as the ‘‘gravity" type, which requires no porous pot. As this may be of use to country experimenters, a brief description is given elsewhere. "G.R.W." (Rodney): Porous pots are generally narrow and tall. ‘They would protrude above the jars, but the latter should be large cnough to give a cireular space of about half an inch) A larger jar than specified can be used to suit the porous pots. Extra size within reason will be no detriment in either receptacle. Sheet zinc, if reasonably pure, could be used in place of rods. but would oftener need renewal _ The two small accumulators snecified are of 2 volts each, the two in series sivine 4 volts. An essential point is not to have too Jarre an accumulator, bet vour 90 amp. hour would be all rievht, esneciatly if von keen on the larve side for dimensions of containers and zine end conner. Don’t waste time mating Leclanche cells for A hattery work-thev run down too auickly and are nseless for the nurnose. The Daniells give constant, thoueh small, current, and the accummmlator ensnres steadv and = increased output when reanired for a few hours out of the twentv-four

Power Valves. D.H. {Taranaki).-Your five-valvé neutrodyne would certainly be bette? with a power-vafve in the Jast stage, which you should attend to first. The valves you suggest are good for first audio, but for second, P.M. 256, of UX 171. An output filter, which can be bought separately, is an advantage to prevent overloading speaker. Five-valves ‘Troublesome. J.T. (Hataitai).-The howling and distortion are caused by the radio-fre quency valye being worked too neat oscillation point, Reduce the R.F. B voltage and get the set neutralised properly, and the trouble should dise appear. In its present state your set will be radiating badly. W.D. (Blenheim).-More particulars of transformer necessary to give any decision. Send rough sketch and gauge of wire on both windings. Browning: Drake. W.J. (Napier) replaced old coils im his Browning-Drake with space-woun ones, as described in the "Record," and reports marvellous results in clarity and tone, and was able to reduce tickles turns from 25 to 10, which shows his set now to be efficient, The only trouble now is the neutralising condenser, which is too large now that the capacity of the set has been greatly reduced witi the space winding. A midget condexe ser, with one fixed and one moving plate, is all that is required. Many constructors have purchased a midget an removed the superfluous plates,