Late repky to a late reply!
I recently bought one of these buses. It was inexpensive because it was missing the remote, the box and had a few dents. When I first opened it up — to smooth out the dents — I was surprised to see there were no active components, like transistors! It occurred to me that this must use some brute force radio reception. Then I saw a picture of the remote and I figured out that is what it must be. Finally I read these posts and now I know!
I presume the coherer is the gadget I circled…(I do not see a “hammer” to undo the connection though?) I am thinking, the market is now awash with cheap wifi based remote switches. If I disconnect the coherer and instead attach such a switch — perhaps over a resistor to simulate the coherer resistance — I should be able to control the bus. Any thoughts if that would work?