unidentified flash coupler

It seems at first sight a coupler to connect a cold-foot/non-foot flash to a hot-shoe camera.

It has no shoe.
At its base there is the hot-shoe contact, at its side a PC-connector.
However at its base is also a accessory contact, at 7o'clock position seen from behind.

The only use of such accessory contact in this case seems to be setting the camera at its synchro-speed.

Inside the coupler is a circuit consisting of
1 diode
2 identical resistors
1 audio amplifier transistor

Sync-voltage reducers have even in their most simple form, more components.

But if it is just to produce that propriatory synchro-speed signal (flash-mounted signal), why is there no camera-brand designation on that coupler??

I'd post a photo of you want to up your chances of a solid ID!

Nothing to show.
It looks like any other coupler of the type hot-shoe/PC, ecxept for it having that accessory pin and electronics inside.
And several cameras have an accesory contact at that position.

To identify the circuit I have to pull out the board. What includes setting the springloaded pins free...
I would rather do that only if someone then actually could identify the function of that circuit.