Controlling everything is a 555 circuit. When triggered, it opens up a relay for one second, which trips the solenoid valve controlling the pneumatic actuators. Originally he wanted to have switches under each target, and only by dropping all four would the reset circuit be triggered. However, he built a simpler solution: a bulletproof button off to one side–effectively a fifth target–that when triggered resets the targets.
HaD have some pretty good shots in our number but we’d probably end up hitting the pneumatic actuators at least once. [Bob] did add 16-gauge steel sheeting to protect the air lines and wires from bullet splatter, which in his experience is more of a threat than a direct hit.
Filed under: home entertainment hacks