a converter for converting a series of digital input bits to an analog output employs a direct current comparator having a magnetic core and primary and secondary ratio windings coupled with the core . the primary winding is divided into two sections . a first group of the more significant input bits varies the number of turns of the first primary section which is traversed by a first direct current . a second group of less significant input bits varies the number of turns of the second primary section traversed by a second direct current . a direct current is also passed through the secondary winding , this secondary current being varied proportionally with the number of turns of the first primary section traversed by the first primary current . modulation - detection windings arranged inside the core detect any net ampere - turns unbalance of the primary and secondary currents in the ratio windings . detection of such an unbalance further varies the secondary current to tend to bring the unbalance to zero . the analog output is proportional to the secondary current . the splitting of the primary winding into two sections enables the converter to handle a larger number of bits , e . g . 20 , than would be possible with a prior art type of primary winding , without the number of turns becoming unmanageably large .