| dc.description |
A sensitive A.C. voltmeter and milliammeter is described and its performance analysed. The moving system is a double repulsion type, using mumetal for the irons, and constraining strips in place of a spiral spring. No pivots are used, and readings taken for small changes of deflection should be of a high order of accuracy. The instrument has detachable coils, so that various ranges may be obtained, and by the addition of series resistances and shunts the ranges could be increased, although this is not recommended, as one of the principal advantages of this type of instrument is its very low consumption. The ampere-turns are 30, and thus about one-tenth of the usual pivoted instrument, and the power consumption about one-hundredth. The watts are 0.018 for full scale of 53°. |
