Update - 22/6/2021 - The logic at the platform side needs to be inverted. On tile load the logic fires an "ON" pulse. The group sensor logic gate on the platform can be set to NOR.
Video Details - Here is a quick tutorial, using some creative uses of mounted spud cannons to activate the traders button. It works by detecting a crate, it fires a spud at a sensor, that "SWITCHES" on. The timing circuit then fires spuds activating the traders button. The system then detects to off signal and fires a spud to switch off the whole system. It uses a very reliable, piston circuit.
The layouts whole purpose was to hide the timing system and cannons.
NOTE: You could wire the platform "OR" gate directly to the far side system master logic gate and achieve the same result. Using the lift underground trick to hide the blocks.
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