A rapid digital-to-analogue convertor for numbers having eleven binary digits

The apparatus accepts pulse signals representing 11-digit binary numbers and from these generates voltages proportional to the magnitudes of the numbers. The output voltage is available for display for at least 400 microsec within 700 microsec of the number being fed in. Resetting occupies a further 300microsec, and the apparatus works continuously on a 1.4 millisec cycle. The conversion takes place in two stages. In the first stage a time analogue of the number is generated by a crystal-controlled binary counter, and in the second stage a linear time-base produces a voltage proportional to this time interval. The adjustment of the apparatus is reasonably simple, and experience indicates that a weekly check is sufficient to maintain 11-digit accuracy.