Digital counter-timer controller for semiautomation of spectroelectrochemical coulometric titrations of biological redox components

A versatile digital counter-timer circuit is described. The circuit simultaneously times and counts TTL pulse events in a single experiment under wither timer or events counter control, or independently times and counts events in separate experiments. The total time duration (1 mu s-999,999s) or total desired number of event pulses (1-999,999) can be preset by means of a 6-digit BCD switch. Initiation of the experiment controls both a timer relay and an events relay. Applications to spectroelectrochemical coulometric titrations of cytochrome c and methyl viologen are described. Applications to additional techniques such as aniodic stripping voltammetry are suggested.