Connect a/b Patchbox Pro gong to the door intercom system

After D I have already tried it. But in the first post I accidentally wrote C. I wanted to edit it just now, but it doesn’t work!? But after C it could then work with 12V permanent voltage, right?

After C you can also do it. But then you have to remove the bridge on the [Patchbox] again.

OK, I will try it.
Thank you.

It only worked to a limited extent. The gong now at least shows a sign of life with the LED. However, it does not respond to pressing the doorbell button. But I think I need to talk to the gong manufacturer about this. The [BDA] of the part is absolutely incomprehensible...