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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?

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    $\begingroup$ My dog does most of those quite readily. $\endgroup$ – user535733 May 28 at 16:50
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    $\begingroup$ Yes, bur it's not a machine. $\endgroup$ – Trismegistus May 28 at 17:09
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    $\begingroup$ Not quite a duplicate, but you may find this question’s answers very helpful. $\endgroup$ – Joe Bloggs May 28 at 19:05
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    $\begingroup$ This isn't a whole answer, but you might find it helpful. kidsdiscover.com/quick-reads/… Also, lots of sophisticated detection methods can be imagined with trained animals like birds that peck a button or bloodhounds barking. $\endgroup$ – DWKraus May 28 at 22:20
  • $\begingroup$ Note that the control with birds pecking a button was seriously investigated during WWII for (anti-ship) missile guidance. $\endgroup$ – Jan Hudec May 29 at 6:54
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Sound detectors without electronics largely boil down to mechanical enhancements for human senses. A room built as a whispering gallery will allow a person in a particular location to hear the faintest sounds at other specific places (like doorways). It's not strictly a pneumo-punk device, but it lets a single person react to sounds in multiple locations over a wide area.

The non-human alternative would be a resonant chamber with a diaphragm connected to a mechanical release -- like a trigger sear. A loud enough sound at the correct pitch will apply enough force on the diaphragm to release the sear -- and trigger whatever you like.

Motion detectors might be things like a suspended floor -- the slightest movement by someone standing on the floor will move the floor and trigger a mechanism. Trip wires also work to detect passing past a particular point, and a wire can be made fine enough that, in poor light, it's almost impossible to see.

Proximity detectors might work similarly to cat whiskers -- fine hair-like rods (bamboo can be shaved to make something like this), holding threads taut, will release tension on one or more threads with the slightest touch, and the release of tension can actuate a mechanical trigger, once again.

Chemical detectors are the most difficult to remove the human factor, and how they'd work depends very strongly on the kind of chemical you need to detect. Flammable gases are the original reason for a Davy lamp -- an open flame inside a fine metal mesh, which prevents ignition from passing the mesh, but will glow with a blue lambence when a flammable mixture is present. Similar devices might detect lack of oxygen (flame gutters or extinguishes). Otherwise it's mainly something that will alert a watchful human, once again -- a piece of blotter paper soaked in a solution to change color when exposed to a particular gas, for instance.

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  • $\begingroup$ Related to the discovery of intruders, check how the Japanese did that: "Created by the best craftsmen and carpenters from around the country, Nightingale floors, or “uguisubari,” which translates as “bush warbler guard watch,” are designed in such a way as to make a sound similar to a bird’s chirping when somebody starts walking on it.": thevintagenews.com/2017/04/16/… $\endgroup$ – Chococroc May 29 at 7:33
  • $\begingroup$ @Chococroc But that's back to simply alerting a human guard, rather than removing the human from the loop, as a proper pneumo-punk device ought to do. $\endgroup$ – Zeiss Ikon May 29 at 11:02
  • $\begingroup$ Thankyou, my initial idea for a sound trigger was a crystal that was somehow tuned to only vibrate when exposed to certain sounds and that agitation would serve as the trigger. $\endgroup$ – Trismegistus Jun 3 at 14:59
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Proximity sensors might be the easiest, but they might need replacement after each activation. For these, your average string work can be used, pulling the tensioned rope allows for springs to return to their position and send an electrical signal through copper wires (copper wires exist since ancient Egypt, so the use of a few circuits isn't that crazy). That in addition to spring-loaded knives and string associations could potentially allow for an opening to be sealed (sustained by the bare minimum strings, some are cut, door collapses and shuts the passage), but understand that, unless you have a secondary system to return it to place while the system is reset (changing all the strings), it'll remain sealed for good. (you could use similar associations by iniciating piston machines, but you weren't that clear about what level of tech you allow these to be made)

The other systems honestly will be hard through ancient technology alone, especially things like chemical and sound detectors. My best guess would be to use another kind of intelligent machines to do this job, carbon based machines. You can train birds and rats to press buttons, so you could have systems that use a hidden button or lever and train these animals to react to a specific sounds (like a dog whistle) by pushing the button or pulling the lever. Train a bird to react to strangers by screaming loudly (birds are very effective siren alarms) and train dogs to react to certain smells.

Although I understand these last ones aren't fully "mechanical" (because I honestly don't think string and chain associations can be considered as such) the fact that you seem to be talking about technology predominantly anterior to the first industrial revolution (beginning of many automation processes), it's very hard, if not impossible to achieve detection systems as effective as modern ones without the basic technology necessary to make them or without the use of advanced machines which already have such sensors (living things have a level of complexity much greater than many modern technologies, let alone ancient ones).

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As late as WWII mechanical listening was used to track aircraft. They were existentially large funnels to channel sound to a persons ears. Usually mounted on a rotatory platform so they could be turned.

It was also common for soldiers in the field to ring their positions with fine lines like fishing lines tied to bells or even to a can full of rocks. They were some times tied to flares or hand grenades.

In the 1980s we relied on chemical detection strips that were suppose to alert us to chemical warfare agents like nerve gas. You fasten the strip to your uniforms. To be honest they did not work very well giving many false positives, like from jet fuel.

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A wide range of chemical detectors could be constructed using glassware tubing and a range of reagents and reactions. For example to detect if a significant amount of carbon dioxide was present in the air, pump (by clockwork, steam or other means) air through a container of containing drying agent such as silica gel, then into a sealed container with some sodium hydroxide on one end of a carefully balanced beam. If any significant amount of carbon dioxide was present in the air the sodium hydroxide would react with it producing sodium carbonate. This would increase the weight and tip the balance which could trigger whatever else you wanted. The silica gel would need to be replaced from time to time and is used to remove water vapour which might also be absorbed by the sodium hydroxide.

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  • $\begingroup$ Any chemical reaction with outgassing or weight change could be used;. Could you create a steampunk spectrometer, to detect specific lines of a gas? See the amplifier bit below; there may be some synergies. $\endgroup$ – asylumax May 28 at 20:04
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You might look into fluidics, or microfluidics: https://en.wikipedia.org/wiki/Fluidics

You can essentially build fluid transistors, and once you have those, you can start to do things like build amplifiers or comparators. Here's a technical report on what you can do with them: https://apps.dtic.mil/dtic/tr/fulltext/u2/a147730.pdf

You can amplify sound as well: https://patents.google.com/patent/US5540248A/en , so, you might be able to have an audio detector of some sort, that could trigger something else.

An amplifier, a bandpass filter, and the rest of that stuff might be able to be built then, without electronics.

The critical part is the amplification of any small change. For example, if a living plant/algae had a reaction that could be monitored, your fluidic transistor might be able to do something with this.

This question might give some ideas:

Sensors for a clockwork/fluidic robot?

coda: There are also opto-pneumatic detectors, so you can do some non-electronic IR stuff http://przyrbwn.icm.edu.pl/APP/PDF/116/a116z320.pdf

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