An ignition circuit (200) includes: an igniter (210) having first (211) and second (212) terminals; a first diode (225) electrically connected in series with the igniter at the first terminal; a second diode (230) electrically connected in series with the igniter at the second terminal. The first and second diodes each have an anode terminal (226, 231) and a cathode terminal (227, 232), wherein like terminals of the first and second diodes are electrically connected to the igniter, thereby defining proximal terminals and distal terminals. A capacitor (235) is electrically connected across the distal terminals and connectable in parallel with a series-connected energy source (215) and switch (220). The energy source and a switch are electrically connectable across the distal terminals via test lead wires. Current flow through the igniter sufficient to ignite the igniter is prevented until an ignition voltage is applied to the distal terminals that is equal to or greater than the reverse breakdown voltage of the first diode or the second diode.