Re-purposing ideas for smoke detectors circuitry ?

Hi.
They are supposed to have very high gain amplifiers; can heart beating, respiration be monitored somehow using a canibalized one ?
What about a hyper sensitive microphone for listening to termites chewing, checking purity of water for particles/microorganisms in suspension, geolistening, ...
What do you know about them and applicable uses ?
Someone wanted to make a geiger counter... would it work ?

Just opamps, use an opamp or two - nothing special about them. Historically there were a number of projects in magazines for making your own, as far as I'm aware you can still buy the individual sensors.

There's a simple one here:

Externet said:

Re-purposing ideas for smoke detectors

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I have never copied a .GIF before. Maybe it will work.
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Thought it might work but no. Target practice.

ronsimpson said:

View attachment 132695
I have never copied a .GIF before. Maybe it will work.
----edited-----
Thought it might work but no. Target practice.

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If I could click like more than once I would!

Nigel Goodwin said:

as far as I'm aware you can still buy the individual sensors.

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as long as you don't buy too many of them... https://en.wikipedia.org/wiki/David_Hahn apparently he used the americium from a lot of smoke detectors to make a neutron source, with the goal of making a working "backyard" breeder reactor... just a neutron source alone can be a safety hazard.