Detection systems and trigger mechanism in a pre-electronic world?

I am building a setting that is essentially steampunk,being exact it would be pneumatic punk. What electronics and electronic equivalent exists, are primitive and extremely expensive. Thus the majority of the technology in use is mechanical.

While I could just handwave all the tech as impossible clockwork gadgetry I'd like to be able to explain what I can.

Without using electronics could...

1. Sound Detectors: In particular those that can be tuned to respond certain sounds.
2. Motion Detectors.
3. Proximity sensor.
4. Chemical Detectors:

Be created and if If so would they work and how could they be connected to a trigger mechanism so that a trap might activate,an alarm go off, or a door open or close?

posted over 4 years ago

Trismegistus‭

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