Minecraft wiki entry for Trap_design, associated text: RS NOR latch / T flip-flop. These circuits take a short pulse and stabilize it. An RS NOR latch uses two inputs, one to set the signal, and another to reset it. The reset switch would be away from the target. A T flip-flop uses only one input which toggles the signal. This is less common in traps than an RS NOR latch because the target could have a chance to reset the trap before they are killed.