Abstract: A digital delay unit for use in blasting operations and the like provides a selected delay between an input impulse signal and an output impulse signal. The delay unit may have a fixed, preset electronically controlled delay period or, optionally, is programmable to enable user-selected changes in an electronically controlled delay lay period. The delay unit has a housing which serves to connect the input and output transmission lines and house the other components, which includes a piezoelectric transducer which converts the input impulse energy, or the energy released by detonation of a booster charge by the input impulse energy, to electrical energy which is used to generate a first electric signal and a second electric signal. An electronic circuit is responsive to the first electric signal to start counting a preprogrammed delay period, after which a second electric signal is emitted to detonate an output charge which ignites one or more output transmission lines, e.g., shock tubes.