A digital counting circuit is described that generates output pulses at intervals geometrically increasing at a rate proportional to the elapsed time, thus making it suitable as a logarithmic time base generator. The design procedure to deliver any number of pulses per decade of time and for any number of decades of time is discussed, and a prototype giving 37 pulses per decade of time with an accuracy of ± 0.5% of the output per decade is described. The unit is capable of starting at 1 &mgr;sec and has an analog output covering approximately seven decades with a range of (0–10) V.