an automatic replenisher system for photographic processors has an improved , digital electronic control . the control includes sensors and signal processing circuitry which provide a signal having a frequency indicative of a measured parameter which is associated with the operation of the processor . a counter counts in response to the variable frequency signal . the counter is interrogated at predetermined intervals , and an energizing signal is produced . the energizing signal has a time duration which is determined by the count in the counter at the time of interrogation .