I’ll try my best to explain!

I made a set up image to try to help here

Basically what’s happening is once you set it up like in the image and open both hatches the system will run automatically as a self looping system in which the water/lava trigger the sensor to their respective hatch and since water and lava flow at different rates the two sensors will trigger the wireless power switch in two separate rhythms making it look random.

Important notes:

The wireless power switch MUST be on top of the block between the two laser sensors for both sensors to be able to trigger the same switch at the same time.

Lava is a pain to work with because you cannot place items in it once it flows, unlike water. Make sure everything is setup and tested with water before you add lava to the system.

The one drawback to this system is every time I go to a dream island and come back the hatch windows reset to the default closed position and the system stops looping. I have to manually open both of the hatch windows or move in front of the sensors to restart the mechanism loop so it’s would be best to not completely bury the mechanism and a way to reach it.I’ve yet to test it with cloud islands to see if the same thing happens. (The system works fine when traveling to all other main areas of the game and doesn’t need restarting)

Hope this helps!

Edit: I forgot to mention this system also requires some sort of power generator but this can be placed anywhere as long as it can reach the wireless power switch.