I think the "chimes" are not mechanical, but electronically produced. The box on the wall contains a small video screen, a button that initiates the camera, a button that trips a solenoid to unlatch the door, a telephone handset that enables two-way audio, and what looks like a small speaker grill.

Power and communications all enter the box through the cable on the right. The other end of the cable disappears into the masonry wall, and ends up at the camera/speaker/ring button, and splits off to the door unlatch solenoid.

Somewhere along the way it gets house current, but I don't know where. There are several possibilities, including a motion sensing light that is independent of the doorbell system and the security cameras, power to the garage door opener, garage lighting, whatever.

I have watched the doorbell delay through the security camera (not the doorbell camera, this is a separate eight-camera system) and the delay is not a fixed duration. I have seen it as short as two seconds, as long as eight seconds. The dogs hear it the instant it is pressed. In fact, tonight I discovered that my pressing the button on the wall unit that activates the camera sets them off.

These days, when the dogs go off, I just look at the security camera to see whether I want to bother with the door at all. By that time, the dogs have already told me that the doorbell is going to ring.

tanstaafl.