Following this! But honestly, these locks don’t seem super secure—more like a suggestion than a real lock.
It’s pretty straightforward. The key switch would arm and disarm the system. Turn one way to arm, the other way to disarm. Nothing too complex about it.
Could’ve been for something other than an alarm too. Key switches were popular for outdoor use or in systems needing some vandal resistance. Computers even used to have them!
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I’m more interested in how the alarm system would work and its history. I assume this was before digital keypads became common? Would there have been sensors in the door frame that set off a siren if opened? Could it be armed while someone was inside, or was it just for when leaving? And was it a local alarm or connected to a security service? Who would have installed these systems back then?
@Raven
These kinds of keyswitches have been around for decades and are still used in various applications.
There was probably a circuit in the door or frame to detect entry, but it’s hard to say without more info. You might find more clues if you look for a metal enclosure inside the house.
Sorry, couldn’t make out much in the second pic due to the paint.
@Rohan
Thanks! The house was renovated recently, so I’m guessing any interior parts were removed.
Raven said:
@Rohan
Thanks! The house was renovated recently, so I’m guessing any interior parts were removed.
Curious why there are two keyswitches next to the door… Maybe one for each door?
Or if the doorbells ran together, it might just be a basic setup that alerts you when the door opens.
Edit: Makes sense if there’s another door off to the right. This setup could just be really simple, where each door has a “siren” or bell if opened while armed. I’m rambling now, but it could be anything!
@Rohan
Yep, my door is on the left, and my neighbor’s door is pictured here. My door used to swing in the other direction, so the switch was close to the knob and deadbolt. My neighbor’s, though, is on the hinge side, as is a third door with a switch.
The doorbell and speaker seem to be for the neighbor’s door in the photo. I have my own doorbell out of frame.
@Raven
Got it! That probably explains the setup in the second pic. If you want to have fun tracking the wiring, it might lead to more questions than answers, though. 
Rohan said:
@Raven
Got it! That probably explains the setup in the second pic. If you want to have fun tracking the wiring, it might lead to more questions than answers, though.
Haha, true!
What’s the black item above the doorbell button? Light? Voice tube?
Drew said:
What’s the black item above the doorbell button? Light? Voice tube?
Good question! I assume it’s a voice tube. It leads up to the open side of the stairwell, possibly for communication between floors. It’s one of those 1880s Victorian details.
@Raven
That’s one of the cool things about old houses—you find all these unique features you’d never see in new builds. We’ve all seen intercoms in houses from the ‘80s and ‘90s, but it’s neat to see something even older that served a similar purpose.