The digital processor is adapted to modify the potential to maintain the current inside a predetermined range such that the potential is representative of the solution pH when {HEAD ~ the current} is inside {TAIL ~ the predetermined range} 
The digital processor is adapted to modify the potential to maintain the current inside a predetermined range such that the potential is representative of the solution pH when { HEAD ~ the current } is inside { TAIL ~ the predetermined range }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL