An old 2C/GPO mains powered telephone bell outdoor repeater/sounder.
To be used outdoors as a portable flooding-imminent alarm , in the
theory that no one these takes notice of car alarm or house alarm piezo
sounders these days.
Quite easy to take apart, 2 stators 150 ohms each and armature 34 ohms
across the commutator, all in series for 240V ac.
Placing all 3 in parallel instead, starts and turns reliably unloaded at
12V Dc, not reassembled with the sounder diaphragm yet .
The klaxon sounder is the same mechanism used in percussion mode of a
hand power drill. Hopefully when the sounder diaphragm is replaced, it
will start and run loud enough on 18V battery pack, failing that adding
another 12V battery in series.
The rear thrust bearing of the rotor shaft has a lockable but easy to
adjust mechanism to change the pressure of the percussion sawtooth
ratchet wheel against the pip of the diaphragm of the sounder (labelled
as tuning) so perhaps allow to spin up no load then engage load and so
noise generation, repeatedly, if the DC voltage is not enough for
continuous sounding loudly.
It looks like the stator coils are only wedged in by thin phenolic
board, so perhaps easily removed and potentially replaced with winding
of coils of thicker wire , retaining the rotor as is, and get more noise
possibly.
Any other ideas to make more noise if necessary?

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
<http://diverse.4mg.com/slr.htm>

When I tried it at 240V ac it was not as loud as the one used in a boat
yard up to 20 years ago. The diaphragm and cone is fixed at the
perimeter by tarred compressed something, with no give at all. I'll try
replacing the gasket with foam rubber and foam washers under the bolt
heads, to see if letting the whole diaghram vibrate increases or
decreases the noise.

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
<http://diverse.4mg.com/slr.htm>