An improved fireset for detonating an explosive includes a voltage monitor arranged to measure a voltage across a quickly dischargeable energy storage device (QDESD), such as a capacitor, and to perform a detonation sequence based at least in part on the voltage measured by the voltage monitor. The fireset employs feedback from the voltage monitor to promote accurate charging of the QDESD and accurate maintenance of charge during an armed state. The voltage monitor also promotes safety by allowing the fireset to indicate when the QDESD is discharged to a safe level, i.e., one which is assured not to result in detonation.