Numerical pulse-width control

The control enables the pulse-width of a clock signal to be set with thumb-wheel switches. The pulse widths are set in five ranges: 1-999 µs: 0.01-9.99 ms; 0.1-99.9 ms; 1-999 ms; and 0.01-9.99 s. These ranges overlap to some extent and this is done on purpose to make available settings like 5.46 ms or 45.8 ms. The circuit has an errar detector that gives a visual indication if the set pulse-width exceeds the per iod of the input clock signal. The permissible timing error is ±0.1 µs in all ranges.